That's kind of why I mentioned the 'mainstream' part as well. If it was just simply ease of use in art/animation, then yeah I'm sure EVERY main character would use something like a club of sorts, but Clubs aren't mainstream. You can blame things like Lord of the Rings and A Song of Ice and Fire on why swords and bows are so popular, since all the main characters use either of those two things, mostly swords though. Same thing with Arthurian Legends, though to a lesser extent than the two things I mentioned prior.
Swords and Bows are EXTREMELY mainstream, so everyone and their mother will know how to draw them, even as concept art for a prop. Thus, time isn't needed for research into viable designs, historical or otherwise.