Not the mention the issue of gender--actually that's always disappointed me about the HDM trilogy, the fact that the author basically admitted that he had no clear reason for why daemons are almost always the opposite gender of a person or what it meant to have a same gendered one...meanwhile most of the zanpakutou seem to have genders. At least we can tell from the ones that have very gender specific names: Zabimaru, Hyourinmaru, Hoozukimaru, Wabisuke... and then the female ones like Benihime and (presumably)Haineko..

I've also always wondered if swordform suggests something about what animal!form the weilder might have taken, had they become a hollow....