It doesn't have to have weapons control, even. If it's limited to an "AI scout" role it could just loiter around, find potential targets and flag them for a human operator. If the targets are reviewed to be valuable enough you could take manual control and fly an assault mission.
The whole process of command and control, targeting, ROE, etc. is incredibly complex and far from easy. Drone's will do more and more, but I'm definitely not a fan of Hunter-Killers on the loose. Two of the fixed-wing losses during the opening of OIF were blue-on-blue Patriot shoot downs: http://en.wikipedia.org/wiki/List_of_aviation_shootdowns_and...
