Not to revive an otherwise dead post but I felt this question deserved some answers.
First thing I should state is I've been helping Sieg work on this project from the start, mostly with the animation tweaks themselves. So when I say things as though I am directly involved this is because I am, and Sieg can verify this.
As far as I can tell the knock back animation is the same regardless of what you are holding.
(I could be wrong as I've never looked for knock back ani's specifically)
Which means with the way an animation edits work changing the off hand from its vanilla orientation could have undesired side effects. The primary example of these side effects being that any item held in that hand would under go a similar rotation along the Y axis.
This doesn't sound to bad until you picture the same knock back animation causing the gun of the off hand to suddenly turn upside down and backwards.
If someone has worked closer with knock back animations and this is incorrect do let me know.
The problem presented here is similar to how mounting a nimbus causes you hold a staff, sword, guns or anything else in the same position. Ideally we would like to make changes for everything to make it look perfect, but the damage it causes to other weapons when the animations overlap makes this unrealistic.
As seen specifically in the case above where literally every weapon in the game uses the same animation.
As for windmill we had looked at editing it multiple times and ultimately failed to see how any movement other then the ones the character already makes would directly benefit the attack.
Holding the sword backwards and attempting to point it straight out would cause you to have to bend your arm in some way. This bend would ultimately cause the Diameter to shrink on that half of your body, this is true of virtually every other imaginable position for either hand.
Ultimately when dual wielding windmill is basically one giant Zelda style sword spin, so logically regardless of preferred sword stance you would want both swords forming as large of a windmill as possible.
I suppose if absolutely insisted upon, we could post a separate file that includes a windmill tweak. We just had not seen a point in changing it thus far.
As for bash we addressed that concern by switching which hand was reverse gripped. I'm not certain if Sieg has posted version two yet but it changes all of the animations to flip the opposite sword, this edit includes bash.
To also answer BrennanM's original post about a custom bash, while making version two we found that there is literally one shared bash animation for all one handed weapons. So rather then creating a custom animation we tweaked the off hands rotation for the original animation.
Bash would of suffered the same problem as knock back if it weren't for the fact that currently, only swords can be dual wielded.
As a fun side note If they ever release a mission that allows Shamala to bash the axe in her off hand will rotated.
I hope this addresses some concerns by the handful of players that have used this edit so far, keep feeding us ideas for stance changes we will try to make them happen.
(this can apply to anything not just dual wield, no promises though.)
As for assault slash I haven't really figured out how to edit a models spacial position without getting a rubber band effect. Anyone that has worked with the animations and seen this will know immediately what I mean.