In a move right out of the movies, he didn't even bother with his blade as his bare hand came up to simply catch her blade.  He held it between thumb and fingers, stopping it as surely as if it had struck a wall.  His eyes fell down to her again, the smile on his face belonging to something more malevolent than a simple shinigami.  "The thing you must remember," Zhou said, continuing to hold her blade even as his own came up, electricity crackling along its blade.  "You must match or exceed the force against you or you cannot harm it.  And at my full strength, you lack the killing intent to harm me."  With that his own blade would swipe down in a powerful blow.  Enough to deeply harm, but not kill.  Obviously he simply intended to step up the training.