Maple/Skills and Equipment

Chapter acquired listed by Web Novel.

If a skill says per day, it should be implied per in-game day.

Equipment Skills
Black Rose Armor (Unique series armor) aka "Armor of the Black Rose" New Moon (Unique Series short sword) aka "Crescent Moon" Mirror of the Dark Night (Unique series shield) aka "Replica of the Dark Night" Mass of the Violet Crystal (Event 2 chest reward, the one with Kasumi)
 * Seeping Chaos (or Oozing Chaos)(Ch.75)
 * Effect: Grants access to the Seeping Chaos skills. Includes 3 skills (as far as I know).
 * Predator: Summons 2 predator devils to fight alongside you. They automatically defeat enemies and have their own HP, attack power, and defensive power, independent of the user. Their firepower and speed are more than enough. Their attacks add Hex. No MP cost.
 * In the Anime: A slimy penis like appendage emerges from users shadow and begins rive and whip like a prehensile muscle, causing damage to its target.
 * Hex (or Binding Spell): Stacks up to 5. Decrease target's abilities by 5% per stack. Lasts 2 minutes per stack.
 * Seal (封印): Returns predator devils to the darkness.
 * Seeping Chaos: Black light oozes out of you, turning the (predator) devils gigantic, and they shoot out like Hydras. Their mouths are said to be 2-meter wide.
 * Seeping Chaos': Black like can also be Hydra's Hydra skill, though damage is not poison.
 * Atrocity (or Savagery): Once per day, You lose the effect of your equipment's and transform into a Devil. You gain a new secondary HP bar with 1,000 HP. [STR][AGI] increase by +50. When your new HP bar reaches 0, you return to your normal form. There is no death penalties for dying in this form.
 * Acquire: (Assumed:) Defeat Devil with HP Drain.
 * Hydra (Ch.9)
 * Effect: Grants access to Poison Dragon skills. By consuming MP, Poison Magic can be used.
 * Paralyze Shout (Ch.10)[Episode 2]: Paralyze all enemies that hears the shout and snap of blade closing into sheath.
 * Hydra (Ch.12)[Episode 2]: 3 Headed Dragon spitting poison.
 * Lethal Poison Breath (or Deadly Breath) (Ch.12)[Episode 2]: Mist of deadly poison from shield.
 * Venom Cutter (Ch.29)
 * Venom Capsule (Ch.31)[Episode 4]: Traps the target in a Poison container and they can't escape from.
 * Poison Lance (Ch.49)
 * Acid Rain (Ch.56)[Episode 5]
 * Acquire: Defeat the Poison Dragon with HP Drain with Poison Nullification acquired.
 * (passive) Foul Feeder (or Gross Eater or Devour' or Bizarre Eater)'' (Ch.10)
 * Effect: A skill that changes everything that was devoured as power. Will devour even magic, and can change it to the user’s MP. When the magic powers overflows, will be stored inside the body as magic crystal.
 * Post-balancing Effect (Ch.20): Limited uses of 10 times per day. The MP that will be absorbed will be doubled. A skill that changes everything that was devoured as power. Will devour even magic, and can change it to the user’s MP. When the magic powers overflows, will be stored inside the body as magic crystal.
 * Acquire: Oral ingestion of a certain amount of lethal substances.
 * Crystal Wall (Suishō kabe) (Ch.57)
 * Effect: Make a wall with the same HP as the user's within a 5-meter radius. Cooldown duration is 5 minutes.

Passive Skills

 * Absolute Defense (Ch.4)
 * Effect: Multiplies VIT by x2. Required points to increase [STR][AGI][INT] multiplied by 3.
 * Acquire: Receive attacks continuously for an hour while dealing and receiving no damage.
 * Giant Killing (or Giant Slayer) (Ch.5)
 * Effect: When four of your stats (other than HP/MP) are lower than your opponent, your stats other than HP/MP are multiplied by x2.
 * Acquire: Alone, subjugate a monsters with four stats (other than HP/MP) higher than your own.
 * Fortress (Ch.54)
 * Effect: Multiplies VIT by x1.5.
 * Acquire: Event 2 Medal exchange.
 * HP Strengthening (Small) (Ch.21)
 * Effect: HP +30.
 * MP Strengthening (Small) (Ch.21)
 * Effect: MP +10.
 * Inhumane (or Savage or Abominable or Devilish) (Ch.10)
 * Effect: Every time you receive an attack, increase VIT by +1, max of [VIT +25]. This bonus resets every day.
 * Acquire: Continuously receive attacks intentionally from an opponent you can defeat for an extended period of time. Do not receive the death penalty until the requirement has been met.
 * Hydra Eater (Ch.9) (evolve-chain from Poison Resistance (small))
 * Effect: Nullifies poison and paralyze.
 * Acquire: Defeat the Poison Dragon with HP Drain.
 * Bomb Eater (Ch.10)
 * Effect: Reduces explosive-type damage by 50%.
 * Acquire: Defeat Explosion Ladybug with HP Drain.
 * Knowledge of the Large Shield IV (or Shield Proficiency IV) (Ch.10)
 * Effect: Reduces the damage received from the enemy by 4% when a large shield is equipped.
 * Body Manipulation (or Defensive Movement or Evasion) (Ch.10)
 * Effect: Reduction of damage received by 1%.
 * Attack Deflection (or Deflect or Parry or Attack Diversion) (Ch.10)
 * Effect: Reduction of damage received by 1%.
 * Stout Guardian (or The Indomitable Guardian or Unyielding Guardian) (Ch.29)
 * Effect: Once per day, endure an attack that would kill you with 1 HP.
 * Acquire: Large shield exclusive skill that can be taken when covering an ally when HP is below 10%.
 * Philanthropy Knight (or Benevolence knight) (Ch.62)
 * Effect: Does nothing. Seems to enable certain quests?
 * Acquire: Philanthropy Knight 2 or further quest chain?
 * Devil Eater (Ch.75)
 * Effect: Unknown.
 * Acquire: (assumed:) Defeat Devil with HP Drain.
 * Venom Incantation (Ch.132)
 * Effect: Poison attacks have a 20% chance of instant death, even if the target is immune to the poison.
 * Acquire: Quest: King of the Pot reward.

Offensive

 * Shield Attack (Ch.8)
 * Effect: Attack using a shield. Power is depending on STR. Knockback effect (small).
 * Acquire: Use a shield attack damage to defeat monsters 15 times.
 * Counter (Ch.73 / 119)
 * Effect: Takes the damage user received and adds it to their next attack.
 * Acquire: Unknown. Related to Event 3.
 * Machine God (Ch.84)
 * Effect: It was a power that destroyed equipment and gave birth to weapons. Sacrificed items of higher quality grant better bonuses.
 * Deploy All Weapons (Deploy Armaments) (Ch.84)[Episode 8]: Sacrifice selected equips for armaments.
 * Deploy-left hand (展開・左手) (Ch.87): Sacrifice an equip for armaments.
 * Commence Attack (Ch.84)[Episode 8]: Fires all the armaments at once. They are not equipment but instead skills who had been enhanced at the price of sacrificed equipment. They do not depend on Maple's STR numbers for damage.
 * Break Core (Ch.147): A hole opens where your heart is and a red glowing spherical sphere shoots out 2-meters away. After 5 seconds, it nullifies all attacks in a set range and self destructs. Everyone in rage suffers immense damage. Maple cannot survive this skill unscathed.
 * Acquire: hidden quest? Although it may never be known if circumstances were done out of order, that the achievement would have been acquired as well. Either way, the quest first required a cog or medal found and the foot of a hill, half impeded into the bark of a tree. Next, an old man needing food and drink must be found and conversed about the history of the 1st and 2nd generation machines. Lastly, the Junk King must be subdued without damage to acquire his trust and grant you his power. If all requirements are met, Machine God status is granted.
 * Pandemonium I (or Parade of Apparition I) (Ch.148)
 * Effect: Call the Red Oni and Blue Oni for 1 minute. The Oni's status depends on your skill level. During this time, all of the user's skills will be 'sealed.' Your equipment's skills will not be sealed.
 * Acquire: Defeat the White Oni past Gate 9 in the 4th layer. (Defeat him again to upgrade it)

Defensive

 * Cover (Ch.21)
 * Effect: Cover an adjacent party member from attacks. When used, VIT is increase by 10%.
 * Acquire: To be purchased from the Skill Shop.
 * Pierce Guard (Ch.90)
 * Effect: An activated skill that nullifies the effects of piercing attacks you receive with your shield.
 * Acquire: To be purchased from the Skill Shop.
 * Loving Sacrifice (or Dedicated Affection) (Ch.64)
 * Effect: Grants access to the Loving Sacrifice skills. These skills costs HP to use. Furthermore, Loving Sacrifice skill must be active to use them (as far as I know).
 * Loving Sacrifice: Allies in an area of 10-meters, centered on the caster, are always under the effects of Cover.
 * Light of Affection (慈愛の光) (Ch.72): (based on maples words, the highest healing spell from Loving Sacrifice's skills that might've repaired the tree damaged by Maples devour from her fall during Event 3.
 * Aegis (イージス) (Ch.84 / 147): A dome of light surround Maple and her allies making all attacks ineffective against them. Duration: 10 seconds. Cost: consumes 600 HP.
 * Self-Offering Love (Ch.?? anime): As long as party members stay within its circle of protection, all damage and effects to party members shall be charged on to the user's HP. Also when active, the user's hair changes to blond and gains a halo and wings like an angel.
 * Acquire: Extra Quest: Loving Sacrifice reward.

Support

 * Meditation (Ch.6)
 * Effect: User recovers 1% of maximum HP over 10 seconds. Duration: 10 minutes. No MP cost. Taking attack actions cancels the Meditation effect.
 * Acquire: Meditate and don't lose concentration while in all kinds of pain for 3 hours.
 * Provocation (or Taunt or Provoke) (Ch.6)
 * Effect: Draws the monster's attention into one point. Cooldown duration is 3 minutes.
 * Acquire: Steal more than 10 monsters' attention at once.
 * Cover Move I (Ch.21)
 * Effect: Ignoring the AGI stat, move to a party member within a 5-meter radius. After used, damage receive is double for 30 seconds. Useable 10 times, recharges every hour.
 * Regardless of distance, as long as friendly target is in line of sight, user instantly appears in front or between target and enemy, ready to defend. (Reminiscent to the Castling Move in Chess)
 * Acquire: To be purchased from the Skill Shop.
 * Encouragement (Ch.42 / 57)
 * Effect: Raises nearby party member's [STR][AGI] by 20%. Radius: 15 meters. Duration: 1 minute. This boost does not affect the skill user.
 * Acquire: Event 2 Chest Scroll. (The chest with Kasumi)
 * Psychokinesis (Ch.56)
 * Effect: You can float a monster (and only monsters). The success rate is affected by resistance probably set for each monster. Failure protects the monsters from this skill for an hour. MP Consumed is affected by resistance probability. (note: As seen with Syrup, Bridge of Bonds pets have 0 resistance probability.)
 * Acquire: Event 2 Medal exchange.
 * Sheep Eater (Ch.69)
 * Effect: Unknown. Grants access to sub-skills.
 * Wooly (or Hair Growth):
 * Acquire: Unknown. (Assumed:) Defeat event Sheep with HP Drain.
 * Quick Change: (Ch.139)
 * Effect: Change to equipment that has been set. Use again to change back.
 * Acquire: To be purchased from the Skill Shop. (Store-advertised bonus. Buy more than 5 items.)
 * Frozen Earth: (Ch.143)
 * Effect: Freezes players and monsters that are within 5-meters of you for 3 seconds. Cooldown: 3 minutes.
 * Acquire: Event 5 present box

Skills in order acquisition

 * 1) Absolute Defense [Episode 1]
 * 2) Poison Resistance (small) (evolved) [Episode 1; Poison Resistance (weak)]
 * 3) * Acquire: Receive poison 20 times.
 * 4) Poison Resistance (medium) (evolved) [Episode 1; Poison Resistance (moderate)]
 * 5) * Effect: Nullifies strong poison.
 * 6) * Acquire: Receive strong poison 40 times.
 * 7) Giant Killing (or Giant Slayer ) [Episode 1; Queen Bee fight]
 * 8) Meditation [Episode 1]
 * 9) Provocation (or Taunt or Provoke) [Episode 1]
 * 10) Shield Attack [Episode 1]
 * 11) Poison Resistance (large) (evolved) [Episode 1; Poison Resistance (strong)]
 * 12) Poison Nullification (evolved) [Episode 1; Poison Immunity]
 * 13) * Effect: Nullifies poison damage.
 * 14) Hydra Eater [Episode 1]
 * 15) Hydra (sacrificed to New Moon skill slot) [Episode 1]
 * 16) Knowledge of the Large Shield IV (or Shield Proficiency IV ) [Episode 2]
 * 17) Body Manipulation (or Defensive Movement ) [Episode 2; Evasion]
 * 18) Attack Deflection (or Deflect or Attack Diversion) [Episode 2; Parry]
 * 19) Inhumane (or Devilish or Abominable) [Episode 2; Savage]
 * 20) Foul Feeder (or Gross Eater or Devour or Bizarre Eater) (sacrificed to Mirror of the Dark Night skill slot) [Episode 2]
 * 21) Bomb Eater [Episode 2]
 * 22) HP Strengthening (Small)
 * 23) MP Strengthening (Small)
 * 24) Cover [Episode 3]
 * 25) Cover Move I [Episode 3]
 * 26) Stout Guardian (or The Indomitable Guardian or Unyielding Guardian) [Episode 4; Silverwing fight]
 * 27) Encouragement
 * 28) Fortress [Episode 5; speculated by BB chat]
 * 29) Psychokinesis [Episode 5]
 * 30) Philanthropy Knight (or Benevolence knight)
 * 31) Loving Sacrifice (or Dedicated Affection) [Episode 7]
 * 32) Sheep Eater [Episode 7; only mentions Wooly]
 * 33) Counter [Episode 8]
 * 34) Devil Eater [Episode 8; not this but instead Atrocity which should be a sub-skill of Seeping Chaos]
 * 35) Seeping Chaos (or Oozing Chaos) (sacrificed to Black Rose Armor skill slot) [Episode 8]
 * 36) Predator [Episode 8]
 * 37) Machine God [Episode 8]
 * 38) Pierce Guard
 * 39) Venom Invocation
 * 40) Quick Change
 * 41) Frozen Earth
 * 42) Pandemonium I (or Parade of Apparition I )

LN Volume 8
Based on the imagine provided in the comments:

Weapon (Hydra), Shield (Devour), Armor (Seeping Chaos)

Bridge of Bonds, Toughness Ring, Ring of Life * Skill not listed above, going by a different name, or evolved skill
 * Heavy Body (ヘビーボーディ)
 * Blessing of Dark Green (深緑の加護)
 * Curse of Mutual Destruction (蠱毒の呪法)
 * Imperial Throne (天王の玉座)
 * Bond with Hades (冥界の縁)
 * Crystallize (結晶化)
 * Huge Eruption (大噴火)
 * Unbreakable Shield (不壊の盾)