be sure NOT to have a dark weapon. I made the same ****** mistake and he WOULD NOT die!!!
try holy weapons, if that doesnt work, check his status before the battle to see what
armor, shields, abilities, and weapons he might have. I know the dark weapons are some of
the strongest, but he just absorbs dark energy.

But Cid will lift his protection so you can give him some damage.

But only if you're at the Final Destination.