Can you describe the pistol a bit more? Specifically, does it have a straight grip or a more hand-filling type? Does it have a safety in the middle of the trigger?
The reason I am asking is that a Model 1913 (or 1914 as some call it) would not have a "eagle N" proof; it should have a "crown N". The only Sauers that were being made in the Nazi era were the "Behorden" model, which is pretty rare, and the Model 38, which is a double action pistol somewhat resembling the Walther PP.