Drones are armed with the standard Collector Assault Rifle.
Drones can have barriers at higher difficulty levels.
Collector Drones should not be underestimated, as they are fairly accurate and can whittle down shields surprisingly fast if not in cover. This can be dangerous if other, more powerful Collector units are present, even more so on higher difficulties. Taking them out first should be considered as they are easier to kill and can be possessed by Harbinger, making them very dangerous.