Full list of all 53 Fell Seal: Arbiter's Mark achievements worth 1,470 gamerscore.
The base game contains 43 achievements worth 1,000 Gamerscore, and there is 1 DLC pack containing 10 achievements worth 470 Gamerscore.
Unlock the Marked Class
Unlock the Demon Knight Class
Unlock Spymaster Class
Recruit Yates
Recruit Bzaro
Recruit Katja
Recruit Kairu
Save Somier a second time
Visit the First Relic
Visit the Second Relic
Visit the Third Relic
Visit the Fourth Relic
Visit the Fifth Relic
Complete the Halloween encounter
Defeat Lady Anquine
Defeat Morgaine
Win the first Tournament
Win the second Tournament
Get the first ending
Get the second ending
Complete the Ancient Path
Drown an enemy
Defeat an enemy with falling damage
Defeat an enemy with a Berserk, Charmed, or Mind-Controlled enemy
Defeat a unit with its Elemental weakness
Defeat at least 4 enemies with a single hit
Defeat an enemy by using a Counter Ability or Thorns
View all optional dialogue events
Unlock all base Human Classes
Master all base Human Classes
Master all special badge Classes
Change Class at least once
Master any Class
Craft your first item
Craft a final-tier weapon
Open 50% of treasure chests
Open all treasure chests
Use your first Class badge
Obtain all gadgets
Cleanse the Cursed Shield
Master all 19 base Monster Classes
Master all Human story character Classes
Complete the Obelisk riddle
Build a Guild Upgrade
Fully upgrade all 5 regions
Complete 100% of Missions in one region
Complete all Missions
Master the 3 new Human Classes
Enlist each of the base 18 recruitable Monster types
Complete all unique Hunts and large-scale battles
Master all 22 Monster Variants
Defeat an enemy with a Pet Effect
Complete an encounter deploying only Monsters