Heroism is self-sacrifice, isn't it?

I don't think going into the mirror universe is heroic. Coming _back_ is. As for taking on the mantel of Ace. He does so *after* being shown that he will die doing it. He could have stayed on Starbug, but he chose to embrace a path that would lead to his death when, technically, he could be immortal. I don't know what that qualifies as but it isn't cowardly.

Oh, I know he's a self-serving bastard, but he has his moments of heroism too. Except that they are ultimately pointless.