Alberto,
My guess is that your rear toggle link might be a spare part from the Swiss Model 1929 Luger made in Bern.
Here is what the rear toggle link looks like on a typical M1929 luger (photo is from the Simpsons LTD web site) :
QUESTION : Do yo see any faint evidence that the flat part of the top of your rear toggle link, behind the knobs, may have had some serial numbers stamped ?
Here is what the plain toggle "knobs" look like on a Swiss M1929 luger from a side-view :
Maybe your rear toggle link started as a plain Swiss one and had some machining and "dicing" pattern added to look more like the DWM type (???)
The other curious marking is on your luger's left-side receiver...just next to the normal C/N (crown/nitro) commercial proof.
I will let other Members speculate as to what this marking might be :