Quote Originally Posted by Kraco
I guess you could theorize a zanpakutou knows itself perfectly and thus can optimally use itself, but otherwise I view that power difference as a giant gap in logic. Unless these zanpakutou will soon start to drop dead due to lack of energy. They are weapons, after all. Where do they get the reiatsu they are spending left and right?
It has been stated that zanpaktous are independant spirits/souls born in their wielder's soul.
As such they probably meant their powers do not need their wielder's power.
But it is true that we do not know how these now totally independant zanpaktous replenish their energy. For shinigami, one would think eat and sleep. But for those zanpaktous it's hard to tell.
Unless the burden is all on Muramasa, explaining his state at times, bloody eyes after a zampktou fight and his seeking for energy.