The fact he'd actually hit floored him. R hadn't expected to feel the shock of the crowbar hitting a body traveling up his arm, the almost wet thud of iron slamming into flesh. He wasn't sure what he was expecting. Weapon-use hadn't really been a priority before.

His surprise made him hesitate, breaking yet another survival rule of conduct. Another Tribute would've been pulling back the crowbar to attack again before Mouse could get up. Go for, say, the squishiest part of his skull and keep beating it in until he stopped twitching. R wasn't that Tribute. His face wasn't distorted by a kill-or-be-killed snarl; it was frozen in a shocked expression, his mouth parted, eyes wide.

Somehow it was different killing someone with a weapon. R's hesitation lasted for a split second too long, leaving a rare opening for Mouse...