Here is the full list of all 24 Alwa's Legacy achievements.
Finish Pacifist Mode
Defeat Imprisoned King
Defeat Sir Pent
Defeat Desmond Grim
Defeat Queen Eydie
Find 100% secrets in all areas
Fully upgrade all magic gemstones
Finish the game
Help a Knight realize her true mission in life
Carry exactly 3 Keys, 3 Tears and 3 Petals in your inventory at the same time
Upon waking up, immediately jump into the water
Reunite a father with his son
Make it over Kloki's Bridge without being noticed once by an enemy
Have the Incantation of Orbis fully maxed out
Defeat all Guardians
Finish the first chapter
Finish the second chapter
Finish the third chapter
Use Incantation of Umbra three times without touching the ground in between
Defeat any boss using only the Incantation of Orbis
Finish any boss without being hit
Kill any enemy from above using a block
Light every single torch in Ancient Catacombs
Transform every Save Point into a Warp Point