[quote="Regulus"]Some models of the Predator drones did carry weapons, before they were renamed the Reapers.[/quote]
Not quite. True, the Predator was the first drone to test out firing of weapons, but that was only because there were no other drones available. When it was shown that a drone can successfully launch a missile, the Reaper was created. Now, Predators might carry defensive weapons, but if the mission specifically calls to shoot at someone, a Reaper is used.