First point - Duel Wielding!
Now that's out of the way... So far the fallout series has been mostly focused on 'city states', independent communities. It would be interesting to have different organization competing for controller, and the play could chose the organization they want to support, confederations, empires, tribal, etc. This would mean that there's a permanent change to the world, beyond the scope of the playable area impacted by the players choice.
Not to mention it's a fun way to impact political bias.
