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[tanglediver]

Any ideas on how to maintain these older knives?

I can tell you what will work the best on your leather bits. Obenauf's Heavy Duty Leather Preservative. I am absolutely sold on this product.
The steel blade is handled much like any tool steel instrument. Choose the proper abrasive product and grit and go to town cleaning up as desired. Then just keep a light coat of oil on it when not in use.