It's been a while since I last fell off the wagon, but fall I did.
Yesterday this one came home with me, it is a Sauer Model 1913 (2nd Variant) serial number puts in 1916.
Not a martial arm per se, but with the arms shortage particularly handguns,
these were authorized by the German Government for purchase by Officers as their side arm in WW1.
Model 1913, Variant 2 – serial number approximately 5000 (with transitional pistols noted in the 5000 to 8700 range) – 134000 approximately.
The magazine safety was eliminated, and the rear sight was improved. Instead of the V-shaped notch the gun has a flat spring on top, the rear portion of which forms the rear sight and also secures the breech cap. (This flat spring latch and sight is reminiscent of the sight for the Bär pistol, which also served as the release for the rotating block. The hole in the rear of the screw cap is eliminated. The gun continues to have serrations only on the sides of the screw cap, and not on the slide. There is an “S” beneath the safety lever to indicate the gun is safe when the lever is down. The thumb grip portion of the safety lever has circular grooves through at least serial number 32121. The circular grooves are replaced by checkering by at least serial number 32482. The hard rubber grip plates are only slightly rounded at the top, with a distinct cutout at the upper left corner to accommodate the motion of the manual safety lever, and the S&S monogram in an elongated oval at the top.