Ferdinand,
Nice rig and congratulations. I've never seen a holster so marked, and it's neat that the holster is serial number marked matching the pistol. Certainly a "keeper"!
Tim,
The Nasjonal Samling "NS" (National Unity), was the Norwegian fascist party active from 1933 to 1945. The Hirden was basically the Norwegian version of the NSDAP SA. The stamping on the holster was the symbol of the Hirdmarine (I believe an auxiliary of the Navy, like the SA-Marine). Like the poster illustrates, the Eagle is a NS cap badge, just like an NSDAP cap Eagle. Attached is photo of a similar style eagle on a Kepi courtesy of Wikimedia. A further check up on the Hirdmarine shows they were established mid-1942, so the stamping must have been applied accordingly.
KK