umm i dnt think its THAT hard to beat Xdeath...
I beat him with all my characters level 39.
with one of the characters i used tht job, forgot what its called, but the one where u cast magic onto ur sword, and attack the opponent with the sword.., well yeah did a flare sword on Xdeath which did 6000-7000 to him, while i put shell and protect on every1 else, and when neo exdeath came i just summoned bahamut, and then got everyone to mime that, and he was gone after about 10turns. the only move he used tht caused problems was tht one the like petrified, zombified, silenced, n confused all my characters.. delta attack i think it was called. Or were u trying to beat him without using mime?