Apologies, Curran and everyone, I did not mean to mislead. It's the same copper tsunagi. I suspect it's a copper alloy because there is none of the usual copper oxidation. The color in the photos is pretty close to the real thing.
The previous post was about kanji on the blade portion, and I got some very helpful info from Jan. This now is about the nakago portion, and thanks to SteveM for the translation, which seems to make sense even though it is not in the "standard" form of a mei on a sword. Regrettable that there's no Natsuo, Ikkin, Yasuchika, etc, Ian. I have no idea what the original blade was, or if there was one. The shape of the tsunagi (hira-zukuri with sori) suggests to me not earlier than Nanbokucho. I'll post a photo when I return from travel.
Les