With his bravery, I find it rather hard to believe that he didn't so much as touch the culprit. Perhaps the culprit did it from a slight distance with the sword? I don't know where they could hide the sword.

I'd be willing to believe that the culprit healed the bruises, but Momota-kun does not seem to have made that kind of motion with his hands.

[...cause his hand was fucking broken.]