What are the differences between koryu and seitei jo? Take kihon, for instance. Seitei jo has the same set of kihon that koryu uses, does it not? I've been told they're done differently (at least some of them) between koryu and seitei, many of the details of the differences I don't really remember and I don't need to know them all anyway, of course, but I'm wrestling with the idea that they're different in the first place. Here's one, for kuritsuke, in seitei we catch the sword on the tsuka between the hands. Does koryu catch under the wrists? I know in a real fight that's the way it's gonna happen, but is it practiced that way? What about other kihon?
I'm not asking for the deep dark secrets of koryu jo, since obviously I'm not a member of the ryu, but mostly I'm trying to figure out why seitei jo exists in the first place (though I'm pretty sure I've figured that one out).