I am trying to get my entity to swap between the two but I am not sure the best method to do this, or how to really.

Look at EntitySkeleton: it creates class fields for both the arrow attack and regular attack AI, then has a setCombatTasks method that it calls during construction, when setCurrentItemOrArmor is called, and some other places to remove the old and add the correct combat task. This is the simplest way to go about it.

Thanks, I didn't know the skeleton used that but it sort of makes sense when you think about it. I think it should work fine for me thanks, just have to tinker some things.