Mike,
My pleasure to help. I've been too busy recently to keep up with the NMB as much as I'd like, but felt I could help on this one. Hope I'm right on all of it.
I do have one minor correction:
My post should read "Higo or Edo HIGO production". In shortest version: Higo style having gained in popularity in Edo (Tokyo) and being a bit far from Higo, artisans (some from Higo and some local joes) set up in Edo to mimick the style for sale locally. Their work is known as "Edo Higo". With tsuba it seems often possible to distinguish Edo Higo from Higo with a fair degree of confidence. With kozuka, I doubt I could say what is Higo vs Edo Higo.
Curran