Hey, been collecting some fight'n rooster knives recently and wondering the ages of the knives I've gotten. One has Frank Buster Cutlery CO. GERMANY stamp. The other gas Frank Buster Celebrated Cutlery Germany stamp on it. I guess I'm wondering if these stamps can definitively determine age? Also one has some oxidation discoloring on the part of the blade protruding from the body when closed. Essentially the top of blade is oxidized whereas the bottom is totally clean, curious if this is a sign of celluloid rot.