Halo

Halos are gold rings that are usually seen hovering above the heads of angels. Onboard the star-cruiser Titanic the Heavenly Host robot work-force had Halos attatched to their heads by spikes. When Max Capricorn reprogrammed them after Meteoroids struck the ship the Host used their Halos as deadly weapons. They removed the rings from their heads and flung them like boomerangs whcih could kill a human with their razor sharp edges in an instant. It is unknown if Max Capricorn designed the Halos to be used as weapons or if the Host themselves thought them appropriate. The Halos appear to be controlled rather than just chunks of metal because even when the Doctor and Astrid deflected them they still came back shortly after and when Banakaffalata fired his Electromagnetic energy the Halos were disabled as well as the robots.