you should be so lucky to find something to off a damsel. I have 2 and they are a pain in the arse when it comes to adding other fish. Anyway, grammas, tangs, clowns (Though they may get picked on), wrasse, really just about any fish will do that is not too easily initimidated by the damsel. They are pretty territorial and sometimes do not take well to new tank mates. You didn't mention tank size, so I just posted some off the top of my head.
To fail to plan is to plan to fail.