Dillon

I though that the kajo was a counter as described above, while the suffix -kyo meant "teaching." In my understanding, ~kyo has almost a religious connotation (bukyo=teachings of the buddha,for example) so the idea with ending the counters with ~kyo indicated that more was being taught than just techniques.

That said, I'm no scholar, and this is just what I put together when musing on the subject.