Thanks, Grey and Geriant - appreciated.
I worked with several groups to help translate the fuchi and was (early on) led to believe it named the swordmaker. Learned from more steady hands this morning exactly what Grey said - this is the signature of the fuchi metalmaker. https://twitter.com/vellum6e/status/943319931248041985
Hi, finally we reached a professional! He explains that this is name of the metalsmith who made this part of the sword. Both 幸雲斎 and 古川 is his professional name as maker and his real name is 忠左衛門 (not written here). He worked for Tosa Domain but he lived in Edo city. He was someone in late Edo era (1603–1868).
Dating on the signature has the fuchi as 1864, as Grey pointed out.
GREY: I grew up in Fredenberg, MN - just north of Duluth. Currently living in Saint Peter but about to start a new job in Jupiter, FL right after New Years. Would have definitely made the trip up otherwise!
Looks like the care and etiquette link you shared is broken. Would love to see a working version and will be sure to read it thoroughly.
Thanks for your help!
Best,
Steve