Hello Johan-
I agree with your observations. It is my understanding, however, that an original issue piece of this sort would always be marked 938. Anything less would indicate a jeweler's copy or something else. I once had a prominent dealer here in the U.S. try and pass off to me a pie-slice PLM marked 925 as an issue piece. I had a number of others look at it as well. The consensus was that it was probably made in the 1930's. This particular award came with photos and additional decorations from the supposed pilot as well. The dealer was quite peeved to have to take it back, but it has always been my understanding that if the marking was less than 938 the Award was not issue. Someone else ended up buying it.... At that point I decided this dealer was operating more on enthusiasm than expertise!
For more info. and examples, take a look at the website
www.medalnet.net HF