It's not far off, but it sounds a little anachronistic to me. The adjective dusdaimon is quite old, and the word daimon itself apparently older--but the farther back you go, the more neutral it is. (The Homeric gods are called daimones.) Fast forward, and classical Greek uses dusdaimon in the sense of "ill-fated." The opposite is eudaimon, "good-fated," and the general idea is this: are the gods/fate/whatever controls stuff
on your side or not?
The Devil (in the primarily Christian
sense, which I think might be implied here--correct me if I'm wrong) is not referred to as a daimon in the New Testament; the daimones there are lesser baddies that go around infecting people. Incidentally, the instances I found of early Christian
authors even using the word dusdaimon consist of quotes from classical authors, e.g. Euripides
So claiming Desdemona
means "of the devil" strikes me as a little off.