Well, just shooting from the hip...
It's a 1938 Mauser [S/42 + Mauser hump] which looks to be in quite good condition...
By 'patina' I assume you mean the blue has oxidized to a brownish color, from exposure to moisture/oils in hands or holster...I like patina...IMHO it shows honest use and age...Cleaning & oiling is good...
Not sure about value; probably in excess of $800+...How much more is best left to the collectors of this niche variation...
