Urm... hehe... i kinda finished the game without the darkknight dresssphere.... can't help but wonder what i was missing... my party consisted of Yuna lvl 77 Gunner(maxed out), Rikku lvl 70 Berserker(maxed out), Paine lvl 70 Alchemist (missing the skills ether and elixer cuz its just too hard!!) when i finished the game... was there a boss fight where it was absolutely crusial for this dressphere? :S