Sounds like you don't really want female armors. You want female costumes and accessories/trinkets. That should be pretty easy to implement, although as others have said, the game currently has no way to enforce genders. You could have females masquerading as males, or vice versa, all the time.
BTW, there are lots of female gamers. The last MMO I played (zOMG) was estimated to be 60% - 61% females, even after subtracting out cross-dressers. Crews were 6 players, and I was often the only male.
Gamer Gurl Gifting wouldn't be an issue with implementing gender, otherwise Havens would be spammed with /kiss every time someone with pigtails/cat ears/tail/ribbon logged in. The idea that a female character will automatically be hit on seems more of a stereotype than the notion that every gamer is a guy. The only real social issue this could cause is sexist guilds...which really isn't that big of a deal, since we have (near) a 1000 guilds.
On one hand, This would be easily implemented. Make a few contour changes to models/armor, give a new "Male/Female/Undetermined" gender option on character creation.
On the other, we can't even get a gunny update to go through on time.