Quote (Austin @ Jan 30 2013 12:46am)
He didn't have to use it on him. He used it to show him hey who cares if you got bankai your not the big dog in the block. Thats why he said "your fangs can't reach me Renji" (You can't hurt me/hit me/touch me/etc.) and then he ended up only getting blood on Byakuya. And he says "congrats your fangs reached me" and walks off with Renji dying under his feet.
Considering all they faught until that point were just Hllows or once in a while a Minos Garda. And Ichigo was killing them like they were nothing and messed up a Minos with a nice cut, without a shikai.
So yes I highly doubt anyone has seen that Senkei besides Renji and Ichigo and well now Tsukishima.
Renji dishonered him and his squad by going up against Byakuya, thats good enough reason to swear to kill someone. Byakuya is of a noble clan and he must "respect and follow the rules" and set standards for all others to follow and admire. So if he had sworn to cut down Renji for dishonering him he would regain his honor and respect so he put a end to Renji's thoughts of being able to defeat Byakuya and save Rukia.
Hrm issues i have with him using it on renji is the fact that he used the word slay(could be a messed up trans but w/e) and then instead of slaying he just wounded.....so i dont think due to the literature used that it was used on renji,..secondly we can all admit this was cliche line "second person or only person to have lived and seen this or to have seen this...etc" yet byakuya although his pride may be to blame didnt mention that ichigo is the second person within a day or a few days time to have seen it. i mean come on, using your best offensive technique never before seen in centuries back to back without mentioning so?
however i cant recall ever seeing him form the cherry blossoms into regular size blades before so honestly i dunno..