You have a very interesting DWM 1920s "Alphabet Commercial" pistol, which, (if the holster markings are authentic), was once issued to the German Labor Corps. It has one matching magazine and a matching takedown tool, (again, if all original).
The finish looks original and this is a very nice rig for someone who collects these mid wars German organization pistols.
It would not be impossible to find a correct, matching holdopen lever for this pistol through members of this site.
The RAD:
http://www.german-helmets.com/RAD_MAIN.htm