Simulating hold types

I’ve looked through the base gamemode codes but I couldnt find anything on this.
I want to have my player cast spells through its gamemode class, avoiding having to deal with weapons so I don’t have to worry about dealing with transfering data between the two (that and I dont really need weapons), but I can’t figure out how to set the player models animation to the correct hold type without a weapon.

Does anyone know how I would go about doing this?