I know it is stamped as a "Puma" but..
Is this a really old Puma blade or a knock off ?

Looks like a Puma to me, from the 1930's. Check out the Puma Collector's site at: Puma Knife Man. Puma Knives, Hubertus Knives, Case Knives, Sharpening Stones & Razors. He has loads of pictures of "not for sale" knives & there is one with a carved bone grip that has a similar stamping. Prior to the now-familiar "Puma-Werke" stamping, there were numerous designs, including that on your knife. I have a Hitler Youth knife with the diamond/Puma head logo that someone replaced the black plastic scales with antler, but did a ****** job. Its a cool old knife at any rate. John