Earth Eater can activate, Greater Sphere creates.

As far as I'm concerned, all Luck does is increase your chance to do a Critical Hit, but since you do 99999 all the time, it shouldn't matter, and "Celestial Armor", which most of the bosses late in the game have, reduces random amounts of damage, regardless or Critical hits.

For example, Nemesis has Celestial Armor. If I attacked with Tidus with any weapon that's NOT Caladbolg, then the Celestial armor would randomly reduce the attack down fro 99999 to a random number. It also creates a different clunk sound with most of the weapons, if it works, rather than a slash, or a bashing sound, which the Celestial Items make.