Rather then having the mods tied to the arms armor, why not have it tied directly to weapon slot itself? As an example: anti overload stasis & kinetic slot, anti unstoppable energy slot, and anti barrier heavy, and we can swap where each anti champion mod is located. I think this is a good idea, since it would allow more build crafting with more weapons able to go into high-end champion content, and freeing up space for all the other arms mods (dexterity mods, reloader mods, momentum transfer, kickstarters and so on...).