You should post in military forum they can tell you all about the stamps
https://www.militaria.co.za/nmb/forum/45-military-swords-of-Japan/
See Boss just posted, yes they NCOs are not signed, it does no good to take handle off and they seldom go back together as tight.
For a plain over cleaned copper habaki it looks fine, patina with liver of sulfur for black.
One step more would be gold leaf...for top half...never paint..
.too tacky.
The blade is very tired ol work horse. Not much can be saved.
No Machi means no polish left.
The Connoisseur's Book of Japanese Swords https://a.co/d/cQbbsP2
Save some $$
John Yumotos is good to have for basics Kanji
The earlier edition is better, better paper stock
The samurai sword,: A handbook https://a.co/d/9DadO8k