This was my take also, that a sear safety was added later. A great piece, but hard to believe a sear safety was added at a later date. No mag safety, so if it was at a police armorery, it would have to have been required (I would think), so I believe it would have been made after 1937 when they were no longer required.
To show just weimar is hard to prove unless a t/pv, or re-proofed, or other indication, like the 1920 marking.
Ed