I agree with your point. If I can't create better swinging animations, I'll simply remove these changes to the starter swords.

Hey, nice to see a response. I have a suggestion for you as someone who's coded my own custom swing swords. You can keep them the way they are with their animation, but instead of (I assume) choosing the beginning angle to be locked to either horizonal cardinal direction (then rotated around the point to place the sword at the "start" of the swing) you can use

(Just for the sake of having a defined variable)
var player = Main.LocalPlayer

player.directionTo(Main.MouseWorld)

to chose the angle of which the swing aims, then rotate the place it starts with RotatedRelativePoint and then use that to turn the sword around the player.

It will let you keep the custom animations but make them a bit more practical with an angle you can choose.

Also, Tangent calculations are nice for having interesting easing patterns if you can fanangle with them and get the multipliers correct.

I really do like this mod, its got a lot of interesting concepts.