Categorizations of historical weapons are kind of inherently arbitrary - most people in-period would have just called all of these "sword", all these classes like arming sword and rapier and sidesword and etc. are projected backwards by historians but the actual real swords don't necessarily fit into those categories that neatly. Terminology around the Renaissance is particularly vague though, since there's very rapid technological development of swords going on during this period (while the arming sword, and the migration-period sword which preceded it, both retained a very similar form for several centuries), yet we see the same term applied to swords from very different points in time - for example both of these swords would likely be called "sidesword", when the first one is basically just an arming sword with a slightly evolved hilt, while the second has a substantially more developed one.

For the landsknecht swords, the one I posted a couple days ago is from a type I've sometimes seen called "proto-katzbalger", those predate the katzbalger by a bit, popping up in the late 1400s, and are, blade-wise, also basically just arming swords - their defining features are the quillons starting to be bent sideways into an S shape (which isn't really unique to them), and the particular styles of the pommels, which are sort of like a cap that goes onto the grip (which is a lot more unique, such pommels aren't really seen on typical arming swords, although similar forms do pop up on messers - so, the proto-katzbalger could be thought of a a messer-style hilt paired with an arming sword blade). The quillons will continue to be bent further until each one eventually wraps all the way around to the opposing side of the blade and the whole thing becomes a figure-8 shape, becoming the proper katzbalger hilt.

And later, those katzbalgers will develop knuckle bows and additional protective bars:

Although that one at least still has the figure-8 guard, just with extra stuff added to it, while the one in the current post doesn't, so labeling it as a landsknecht sword is indeed kind of dubious. I guess the particular grip still sets it apart from the more typical basket-hilted swords of the period, but still. Anyways, these tend to be from the late 1500s, by which point the landsknechts are starting to disappear, and so does the category of "landsknecht sword".

As for the length - even among proper katzbalgers there is some degree of variance (as will be the case for any style of sword which isn't mass-produced according to a specification), there are indeed pretty short examples but also some which are comparable to arming swords. For example this one is supposed to be 88,4cm - the lower end of arming swords is generally around 90cm, and a lot of the typical high medieval examples are around 100cm, so it's not that much shorter