Yes, there exists an illustration, thusly... but I still wonder if the text doesn't still refer to mortschlag... just not illustrated correctly.
It wouldn't be the last time that picture commisioner/editors don't know wft they are doing. How many APC have been referred to as "tanks", or used as illustrative of "tanks" in our modern media...
I don't see how throwing a small smoothly contoured 'rock' at your opponent will be likely to "rightly" end an opponent (even assuming it hits), while I do see how crushing their armour &/or bones with a solidly delivered pommel strike could do so without partially or completely disarming the fighter. Further I can see how a transition from half swording with a 'short point' to a 'warhammer' with the pommel "thrown" to a much longer reach could be described using this phrase.
As HEMA is about interpretation using biomechanics and martial effectiveness to form at least part of the 'technique' from the somewhat sparse textual and illustrative material I don't think that there is a reasonable explanation of how this could work as drawn. FFS they are wearing harness, and have effective weapons in their hands... and this 'fiddling' is supposed to accomplish something?? Don't buy it for 1 second.