Avatar animations: what limit they impose on weapon availability to classes?

I know I can't have a staff-wielding monk because they lack two-handed weapon animations. What other limitations there are? I would assume the same applies to thieves (at least with great swords), but there are mods that allow all classes use any weapon and I doubt they come with a bunch of their own animations, so there might be a trick to it.

For one, there are flaming swords which must use the standard sword animations. If I decide to make katanas two-handed, will I be able to simply say 'use a two-handed sword animation with this sword image', or must I redo also those animations with an appropriate-looking sword in its place?