Proper Unity and Blender Weapon Rigging and Animation

Hello,

I am working on a multiplayer shooter game, and have gotten to the point where I can not put off properly animating any longer. Right now, I have a blender mesh and armature for my whole player body, just the arms, and then all of the weapons. For each weapon, I have a blender file that links the weapon and arms so that if I change the original one they update accordingly. I make the armature objects proxies to be able to edit the pose. The problem is that there are two different armatures, therefore they have two different animations. I tried parenting both proxies to the same object, but it keeps creating an animation for them individually instead of belonging to the parent. Am I fundamentally setting up something wrong? It seems like this should be a pretty common thing and I am having a lot of trouble with it...