I've thought about this. some more. I don't think there are any character traits that are sexy in men that are not also sexy in women. The new, more modern, pop culture feminine sex symbols emphasize the same traits that are found in men. Things like assertiveness, confidence, competitiveness.
However, that doesn't mean they are equally common in men and women, and they certainly aren't expressed in the same way.
Also, there are an awful lot of traits that can be expressed by men in ways that are generally viewed as admirable, or that are generally viewed negatively. Take competitiveness for instance. If a man gives his all, always puts forth a maximum effort, shows perserverance through difficulties, whether in serious situations (wars, life threatening situations, really important stuff), or in games and sports. I think people admire those things in either men or women, but expect them more from men. On the other hand, some men have more of a "win at all costs" attitude, or they get visibly agitated when losing, show aggression, complain, yell at people. Those are all associated with being competititve, and also with being a jerk.
Some of the same things can be said about women, but there is one major difference. It will be said that our society doesn't value those traits in women. Women aren't supposed to be competitive, and they are looked down on if they are. That's sort of true. What I think is actually the case, though, is that women who are good at things threaten weak willed men. Until recently, our society would have encouraged women to back off and above all never, ever, defeat a man, at anything. There was fear that men wouldn't like it, and as a result wouldn't marry the woman. Today, I think there's a whole lot less of that. There are still men who are threatened by strong women, but I think more women are likely to say, "Who cares?" and look for a guy that is sufficiently confident that he doesn't feel threatened by people, especially women, who are better than them at, anything.