Interesting question!

Unfortunately I'm not an expert on this topic (or any topic, actually), but by coincidence I've given a doctoral thesis on the topic of Fechtbuecher [1] a bit of attention recently.

There is a whole subsection about Dueres work (III.3.6, Page 161-171) which could be summarized as follows:

• Duerer hat intrinsic motivation of drawing people anatomically correct in different and difficult stances. The thesis thinks its likely that this was the main motivation for doing the work and cites [2] for that.

• It is probable, but not proofed, that Maximilian I was the one comissioning Duerer to do this work.

• Durer probably did know quite a bit about fencing: For one it was common for citizens of cities (especially for "Freie Reichsstaedte" - free imperial cities, which Norinberga was) at that time, for two it is very obvious from the pictures that he did know a bit about topics like weight shifting, evasive maneuvers, parades, etc. So he probably practised fencing as a hobby, like we would do play football today, maybe was even quite good at it, but probably not a well-known master.

I hope this helps a little and does comply with AskHistorians quality standards :)

If you can read german, that would should at least be a nice starting point. Its quite exhaustive about fencing books and has tons of sources (most of them german, unfortunately) and explicitly states a lot of context which helps understanding the situation.

[1] https://elib.uni-stuttgart.de/handle/11682/5275 That should be open access.

[2] Dörnhöffer 1910; Dörnhöffer, Friedrich: Albrecht Dürers Fechtbuch. In: Jahrbuch 27 Heft 6 der kunsthistorischen Sammlungen des allerhöchsten Kaiserhauses, Wien-Leipzig 1910.

EDIT: Formatting issues fixed.