For playing Final Fantasy XIII, I received a Key Item called "Eternal Crystal". Most Key Items don't really do anything outside of reminding you what you have for purposes of the plot. Does this one do anything special sometime though since it's optional?
What does the Eternal Crystal do
final-fantasy-13-2
Best Answer
The Eternal Crystal doesn't do anything: it's just there for bragging rights. If you play on the PS3, you also got an extra theme for playing Final Fantasy XIII.
Most key items do have a purpose, though: