Thank you for sharing, Rich!
One comment about the possible knife maker:
Some bear the stamp (in Cyrillic) “A. I. Borisov,” which could refer to a factory or foundry in Barysow, Belarus, long an important industrial region.
I suppose, “A. I. Borisov” is the name of the person who made the knife, not a factory or foundry in Barysow. It were a lot of private knife makers in Russia till about 1955. The stamp is tipical: initials of the first name and middle name, the last name follows. Borisov is the wide-used Russian last name (from "a son of Boris").
And almost any Soviet factory had stamps consists of the first letters of the factory name (like U.S.S.R.), not the city.
But it's my speculations only.