Asterigos: Curse of the Stars

All materials are fearly easy to find except for one : disintegrated star core. It's needed to level up a weapon from 9 to 10 (max level) and there are only three per playtrough.

1) Story related after taking down Titan.
2) In the last chest of the game, just before the ending boss.
3) In a locked chest in Phalan academy (barrack). Requires Marble's personal key to open (story related).