I think when Ken says he "gave it his all" what he was basically saying was "I didn't hold back". Essentially his way of saying "I killed him" to Yachiru. That's the impression I got from what was said, and what their expressions were.

Quote Originally Posted by Mizuchi
Yes but ichigo didn't use it in his fight with Zaraki.
Are you sure about that? If you remember in that fight, when the both charged at each other for the final attack, Ichigo's reiatsu took the shape of a giant Hollow mask.