I see your point of they were using a baqll point pen but I have many after war sigs with use of a Flair type marker which is crap and not fully detailed, fully "flat" as you mentioned, no indentations at all. Sadly many KM pics are signed right over the dark blue tunic/coat with black or blue pen so you do not see the full sig as it literally melts right into the dark background.......sniff, wimper

I have a rare signed pic of KM H. Bögel in black ball point, clearly hand signed, very nice sweeping signature he had but right across his neck and part of his face........yikes.

Siegfried Wupperman. Horst Weber, Felix Z. and a couple of other RK S-booten winner pics I have are all signed with black pen and are very hard to read except for Kemmnades which is in Blue as well as S-boot ace Kurt Fimmens. At least the Töniges pic had a white area at the bottom for his black marker sig which is very clean and crisp. Kleinkampfverbandführer Helmut Bastian's pic signed with Black marker pen to the lower right but very crammed together which was his style but hardly discerned. G. Priens is very clear and clean in black ink.