The color of the holster does not indicate anything about the branch of service it was issued to. I'm not sure who started this rumor, but I think some books were published that had this mis-information in it, and it spread.
As for the DH marked holster, I'd have to see it to confirm it. These are extremely rare, and most often are fakes. Did you happen to take photos of it? If so, please post them.
As for your 1936 Mauser Luger, there are good holsters out there for it, you have to search. You could try some of the dealer sites. You'll pay a bit more, but I'm sure you'll find one. Otherwise, search the forums for sale sections. I've found many good holsters there!
Hope this helps,
Matt
