For Avatar personal headcanon, I like the idea that Aang holds back in his fights. We've seen him fight a volcano and win, something Roku himself failed to do, so he's not lacking in raw power as a bender. Yet when Azula or Zuko show up to tango, he often ends up with his back against a wall. I think Aang really handicaps himself in fights, trying to use the least amount of force necessary because he's aware how easily he could hurt/kill even someone like Azula.

When he fought Ozai, we saw Aang purposefully miss redirecting lightning back at Ozai for an easy kill shot, and Ozai was in the process of burning down the Earth Kingdom. That's the strength of the personal morality that drives Aang to restrain himself in all his fights.