So for meshes like Grim Reaper and Aquaman Harpoon, how might I make it so that the dominant hands are switched, both in keyframes and nif, I'm aiming to put and aquaman bod on a grim reaper keyfram set, to make a spinning harpoon effect
As far as I know, since the keyframes actually control the bones they move by the name of each bone, that would be difficult. You'd have to rename the bones in each arm by the other side.
Kenn X actually has some left handed kf for some of his meshes - some of the Blackhawks I just worked with, but nothing fancy like you want.
It would take someone with tons of skill above mine to do it. Of course there might be an easy way I'm not aware of.