„D.R.G.M.“ – „D.R.P.“ – „GES.GESCH.“ - "D.R.G.M. ANGEM." … such markings are showing up occasionally on knives, edged weapons and other items and are proving property rights of the owner, mostly of the manufacturer.

Rights for inventions could be protected as ‚intellectual property‘, since the (German) Imperial Patent Office („Kaiserliches Patentamt“) was established by law in 1877.
Everybody could apply for a „D.R.G.M“ (Deutsches Reichsgebrauchsmuster – ‚utiliy right‘, small/petty patent, low invention step) or a „D.R.P.“ (Deutsches Reichspatent – German Imperial patent).

The Imperial Patent Office confirmed the inventor’s application prompt, anyway it took some time for the authorities to prove the application prior to granting the right with date and D.R.G.M. or D.R.P. number. Such protection right markings could be used legally only while the rights were being granted (… and the right had not yet expired).

[Linked Image from i.imgur.com]

Therefore makers quite often used markings such as „D.R.G.M. angem.“ („angemeldet / applied for) or „GES. GESCHÜTZT“ (gesetzlich geschützt / protected by law), to indicate, that rights were not yet granted as ‚warning‘ for competing makers, not to copy such items.

Referring to Anton Wingen’s ‚DEUTSCHER BRUMMER' knife I am convinced that the 1930s catalog’s illustration with the „GES.GESCHÜTZT“ mark and missing 'D.R.G.M.' has a simple reason:
The handmade dies for printing the illustration were being crafted while the knife's design was made and while a protection right had been applied for. Anyway the right had not yet been granted by the Patent Office, ... probably sometime prior or during WWI. For new editions of sales catalogs or for promotional use the ‚original‘ die was used, there was no attention to the fact, that the D.R.G.M. had become effective in the meantime.

regards
chevalier2022