Hmm. Are you speaking of film or literature, or both? Epic fantasy is filled with guys wielding swords, and a few females, too, but in the real-life scheme of things, a woman competing with a sword on a battlefield is likely to have a somewhat shorter life expectancy unless she is really, really good (and I'm a girl who once was in the Army, running around in field gear keeping up with da guys, so don't hit me).
Most of my high fantasy is written with a male in the lead role, but my first book, Firedancer, has a strong female lead, who has her share of problems with gaining acceptance but doesn't back up worth sh--, eh, beans. I have seen the discussions that ask whether women can write SF/fantasy as well as guys, with some guys admitting they shy away from female names on the cover and others declaring it makes no difference. I do know that some female writers deliberately avoid putting women in the lead role because they feel the male audience will not want to (or be able to) relate to a feminine point of view. I think there is a general fear of girl cooties and "mush" when the protag is a woman. This, unfortunately, leads to the general preponderance of butch, kick-butt, steely-eyed females who are basically guys with boobs and not allowed to be women.
There are, however, some really excellent female characters in SF. C.J. Cherryh writes excellent secondary female characters, like Mallory in the universe of her Downbelow Station, and Ilisidi in her Foreigner series, but those are SF, not fantasy. Her lead in Gate of Ivrel is a strong woman with a kick-butt sword. You might try that one.
If you look beyond epic fantasy to, say, urban fantasy, you get into cool characters like the lead in Emma Bull's War for the Oaks which is a fun combination of hard rock and Faery. But I agree that you sort of have to look hard for high fantasy that uses a female lead. Whether that is a combination of authorly fear, an accurate reading of the likelihood of audience acceptance, or a bow to the realities of medieval-type warfare, I don't know for sure.
Or maybe other women authors, like me, find it's just fun to write guys!