Here is the full list of all 21 Clash: Artifacts of Chaos achievements.
Hit all targets with rocks while training at the parry machine
Create 5 weapons
Learn 4 special attacks other than the Spin Kick
Find all special attacks
Reach the highest elevation point in the Salt Marshes
Reach the highest elevation point in the Northern Ruins
Reach the highest elevation point in Corwid Territory
Defeat the Outcast
Defeat Axylon
Defeat the Director
Obtain 9 pieces of armor
Obtain 18 pieces of armor
Obtain 14 body parts for the night avatar
Obtain 28 body parts for the night avatar
Defeat Wrehgg
Defeat Claw
Defeat Moon-Sun
Defeat Gemini
Defeat Nightmare Claw
Defeat Nightmare Moon-Sun
Defeat Nightmare Gemini