My view is that Genma didn't have access to the actual weapons (and,
in any case, wouldn't teach techniques that worked only on specific weapons) but that Ranma has learned generalized weapons use/defense
as practiced by Saotome-ryu.  This is different from the refined and specialized (and probably more effective) techniques of weapon use that Akane was taught. That's my story and I'm sticking to it.  :)