Hermit, the swastika in a circle is the standard proof mark that began in 1939 with the tail end of the S/42 and the front end of the Code 42 pistols. The markings are standard military and I know of no connection to any one group, unless it were Kriegsmarine marked and it doesn't appear yours is. There is no connection between military holsters and pistols. The supply people put a pistol with whatever holster was on the top of the box.
Regarding the grips, I understand your concern. The right grip is stronger that the left, so it is recommended this one is removed for inspection. One can observe the back of the right grip and with the magazine removed, you may be able to see any markings through the frame on the left grip. Good Luck and <img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />