Ok, this is getting weird. Aren't zanpaktou susposed to be unique? So how come Isshin have Zangetsu attack? Father/Son doesnt mean they have the same zanpaktou? Oh well, Squadzero is right by saying ti the new kamehameha wave, same shit as rasengan... Guess only one piece and fairy tail are keeping it uniqueness.
@Squadzero, Zanpaktou are "part of the shinigami's Soul" or so it susposed to be, just like how Ichigo could call ti from his soul many time. Yoruichi should be able to do the same.