It would be refreshing to see the bad guy plead, "Finish me," and the hero reply, "Fine!" and do it.
You don't see it as much anymore, but what used to rile me up was the scene where the two antagonists are fighting on a rooftop or edge of a cliff; the villain leaps, usually after he seemed to be defeated, and the hero steps aside just enough to let him go sailing off the edge. The villain gets killed, but the hero didn't have to actually do it.
I'm sure this is at TV Tropes but I've sworn not to go there on a worknight.