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