I look at these bloody portrayals of fighting the way I do with Talhoffer and Mair; they show effects of what happens if you do these actions "all the way", and to mark more clearly where you are actually hitting (often both the arm and head simultaneously), but not how they generally were performed in training or the fechtschulen. It is pretty reasonable to believe that men that relied on their eyes and fingers for a living also made sure they didn't take serious risks of loosing them unless there was a substantial monetary incentive to do so. The material on rulesets from fencing guilds that has thus far been put forward seem to indicate this as well.
Mair does indeed show this, not just a few times, but especially when cutting with the middle of the blade.
As for the treatise discussed I do get a feel that it is, if not related, then at least partly stemming from a close root. Few other sources show staff fencing holding the end of the staff like shown in Meyer and this treatise and in both there are plenty of single hand strikes and thrusts. Furthermore the triangle step and the specific body mechanics is similar. In the Halberd section of this treatise I think there is a stronger focus on gripping the halberd near the head though.
The longsword section is trickier, and surprisingly enough seems to use no terminology at all, apart from short/long edge.
Turning to the dussacken, the guards at first appear odd, but upon closer examination we see something resembling the Eber, Vacht, Zornhut, Steur and Mittelhut + a few other peculiar guards, like the "hit me in the balls"-guard.
Very significant for this treatise is the use of the left hand in the Dussack fencing.
Looking at this treatise I actually get a very strong sense of "action shots" rather than images with posing to illustrate specific techniques and principles. I also find it interesting that the targets are so clearly marked in this treatise.