My pleasure, Stephen. I hope you update us if and when you determine the original owner.
As far as cleaning it up: First of all, it's in really great condition! I'm not even sure if it was used or sharpened after it left the shop based on your photos. The only real condition issue is pretty severe oxidation of the aluminum butt cap. It may be possible to remove the nut and clean it up, but I wouldn't recommend it for two reasons:
1. Any significant cleaning would reduce the market value. For example if you sent it in to the Shop for a "cleaning", it will be reground. IMO the value would be cut in half!
2. "As is" condition is the visual representation of the history of the knife, which would be lost forever.
I can tell you what I use for my knives in a similar condition:
1. Leather handle: Lexol leather cleaner and conditioner
https://www.amazon.com/Lexol-Leather...HH5X8YREGDTG6Q
Without some moisturizing, the leather will continue to dry out and shrink.
2. Blade: I
lightly remove the 1st layer of rust. Any metal cleaner should work. You don't want the blade shiney! Then I apply a thin layer of a product called
"Renaissance Wax" to prevent further oxidation:
https://www.google.com/search?q=rena...08521791222312
3. Butt cap and retaining nut: I would leave these alone.
Let me know if any...…..
PS: As an aside, I have cleaned up a number of old rusted tools by an "Electrolytic Rust
Removal" technique I found on line quite a while ago:
https://www.wwgoa.com/article/removi...electrolysis/#
The results are pretty amazing.