Al this is very valid info and i know about these principles of animation, its called overshooting , when hitbox frame is extended/stretched a bit beyond its range and goes back on next frame.I did it with with motion blur in front tho , but i think ill just use that on all attacks anyway with follow motion blur, im just not a fan of it in front and thats usual case when its used for overshoot
All this and more is nicely written about in this pdf for skull girls, i recommend it to everyone who wants to animate attacks and animations for video games.
https://ubm-twvideo01.s3.amazonaws.com/o1/vault/gdcchina14/presentations/833784_MarielCartwright_PowerfulAndEffective_EN.pdf
https://www.youtube.com/watch?v=Mw0h9WmBlsw
I experimented with overshooting on this one but it just didnt look as good for me as with motion blur.
About motion bliur being in front , it is physically incorrect when its in front of body but, imagine that a slight move back happened between anticipation frame and next frame, and you can justify motion blur.It just looks better when its in front, it looks unnoticeable when behind the body, so you have to cheat and play for the camera.
Also important rule for blurred frame is that when your 1st frame has hand hear your stomach and next one has arm it extended then your blur should start approximately where your stomach/hand were on previous frame ,if its noticeably longer ( like in my case) or shorter then blur looks less impactful or just wrong unless extended blur range is not that big,.But absolutely you can use short /longer ones for different types of timpact just be aware that it might not work , more important is the angle and "(" shape of the blur itself , bent ones, astraight ones look different and give feel of a hook or straight punch.
OK i will paste the image with various dynamic poses i gathered from games in case i will lose it.