I think both are cliche to me, but sustaining a harsh injury may be the bigger "offense" in my mind at least. People are bound to get hurt when everything and everyone clashes, Asami and the others included. I am sure [i]everyone[/i] is going to get out of that battle with some kind of physical injury but at the same time, Asami is the only one without real fighting experience so in my mind, everyone else should have [i]some[/i] kind of upper hand in not letting Asami's attacks do as much damage to say, civilians. Mako, Korra (etc) are skilled enough to minimize her attacks, not go unscathed but to at least know better about dodging/deflecting. At least to me, I don't see major injuries being conducive for development's sake. If Mako or anyone was awfully hurt, Asami would really find it hard to fire bend, and sure it's Xano's and Xana's fault, but it would still make Asami seriously consider giving up bending if it hurt someone, her mother did die in a bending incident after all, I don't think she'd handle it well. Broken bones, first/second degree burns, cuts, bruising, mild internal damage are fine but anything long lasting like a lost limb, serious scar etc just kind of make me roll my eyes. Maybe that's just me. 

And a thought I had, we could have Xana give Asami something to give Lin and Tenzin to change them into a younger self, since she will be reconsidering why they're doing what they're doing.