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