Here is the full list of all 17 Thy Sword trophies - there are 4 bronze, 2 silver, 10 gold and 1 platinum.
Get all other trophies.
Finish the game.
Gain all five crystals.
Kill the Lich King & Queen.
Kill the Sorcerer of Thorn.
Kill a flying enemy with an arrow.
Kill the Dragon Lord.
Get killed by an explosive barrel.
Kill the Lurking Horror.
Find the secret gate to the loot room.
Kill the Spider Queen.
Chop 15 heads enemies in one game.
Headchop an enemy.
Get the key to a chest.
Finish the tutorial.
Get hit by your own arrow.
Hit the lantern on the title screen