Why is that secondary nazi symbol on his glove in the second frame? This is1919, and at this point the "nazis" was a small political group with like 20 people......so I am confused.
The sign was used by the Nazis, however the iron cross is older than them like alcoholicorn said. You can still see it on a decent amount of German military equipment.
Also not to mention in this context it's supposed to resemble the x mark you'd see portrayed on treasure maps.
The Iron Cross was an old Prussian symbol before the nazis adopted it, used as a military award. It still was used in military contexts for quite a few years after the war, IIRC, the finns stopped putting it on their planes in like 2016.
It would probably have been known in 1919, WWI and all.