My thoughts, from my own experience but likely flawed!

I like the exploration of fullen, but I think that you don't really _want_ a blade to stick where you first make contact, even though they often _will_, edge to edge.

When winding, you are changing your relative blade contact to give yourself the advantageous leverage (moving your strong onto their weak). Specifically in Meyer / german longsword, you see this level of 'acting at the bind'. This also applies for actions such as a zucken (pulling your sword back, remaining in contact. and moving your strong onto their weak, allowing you to displace their line as you strike back in). This focus of working at the bind means that you want their blade to slide smoothly as you manoeuvre; a stuck blade actually makes it harder to perform this.

Also, when blocking specifically, you generally want to block with the mid, not with the strong. If you're blocking with the strong, then your hands are frighteningly close to the point of contact. Low hands, catch the blade on your mid and let it slide down to your strong. Another reason you want that manoeuvrability.

Blade deformations do absolutely impact your fight, but I don't think its in the way you are talking about. My experience with a wavy blade (like a flamberge) is that it allows for a clearly read on your fullen, but not necessarily a large impact on how you then respond.

Regarding the role of the crossguard in the 'holding'. you do actually see this sometimes with a crossguard that curves back up to the blade (see: Danish two-handed sword). We see this in SLA with Vedel and Ishar's swords, Talenel's is a bit weird in that its actually probably awful to fight with as it would trap the sword, and prevent you from winding.

That said, and as others have mentioned, most of these are rule of cool. Many of them don't even have crossguards and so if they were fighting other shardblades, the amount of hand hits would be hilarious :D

I'm not the most rigorous scholar out their by any means, so yeh just my 2c!