To explain the Disabling of his arm: That's his end goal, not his current goal. He's trying to numb the arm with repeated strikes, this is just one of many. Sorry if I wasn't entirely clear about that. The upward strike would have three times the effect of a normal strike, as his rings add 2x the force to each strike on top of the normal strike. Making each strike 3x as effective as a normal strike. It wouldn't break or even come close to disabling his arm as of yet, but since his arm was already struck by a previous blow, a follow up would cause it to sting even worse. 

And on Kanitah's nasal bone; Cracked, as in slight breakage. Like, barely a splinter, but still noticeable enough to cause pain. Nothing that would cause a nosebleed, and not even a significant enough injury in real life for someone to stop fighting. But remember that Kanitah is old. Certain things are worse on him than they would be on other people.