Here is the full list of all 35 Eternity: The Last Unicorn trophies - there are 20 bronze, 10 silver, 4 gold and 1 platinum.
Upgrade the Eir medallions at the maximum
Upgrade a character at the maximum
Beat the arena mode with a character
Finish the game
Talk to the Oracle in the Yggdrasil Garden
Defeat Gullveig
Ring the bell in the Gullveig's tower
Defeat Skogul for the second time
Release Zenogb from the witch's dungeon
Purify all corrupted bodies
Beat all the arenas
Defeat Helviti
Defeat Erick, The Corrupted
Defeat the Swamp Tentacle
Get the long jump
Upgrade the elven sword at the maximum
Upgrade the skadian bow at the maximum
Collect 10.000 shards
Defeat the Old King Wolfric
Deliver Durin's hammer
Defeat Skogul for the first time
Defeat Úlfrstórr
Release the fairy
Get the Skadian Bow
Defeat the Spider Queen
Find the lord of the forest
Get the light flask in Makala's temple
Collect all the trophies
Upgrade the sword and shield at the maximum
Upgrade the two-handed sword at the maximum
Release all bodies corrupted by the swords
Collect all scrolls of Elros
Complete the book of biographies
Collect all the chests
Forge 10 different items