Thanks everyone for your thoughts and ideas. That's a lot more than we started out with, but I have to say I'm still not satisfied that we've gotten to the bottom of the whole story. I'm with Allen that the equivalent of "A,B,C Sword Method" is a pretty thin appellation for a realization direct from all the Kami of Japan to a man who didn't shy away from the grandiose.
"All the gods of Japan gathered and brought aiki truly into life, fostering universal spirit and ACME Swordsmanship."
That said, before we started I didn't know that the name Sho Chiku Bai Kenpo used by Ueshiba himself so that alone is worthy of gratitude.
edit: Josh, thanks for clearing up the Shinkage aspect. I think we were led a bit astray based on a conversation with Ellis that we probably read too much into. But not so far as to link Ueshiba's or Shirata's ken to Shinkage other than to note that we were on the mat with a Yagyu guy and a THSYR guy and we all three knew a kata (singular) that is pretty distinctive.