The Heretic ghost is a ghost used by the Elite Heretics on Threshold. These Ghosts were used by the Elites, but were soon found to not have much use on the mining platform, many were currently not used or destroyed when the Arbiter came to eliminate the Heretics, because the Ghosts were obsolete which is why they are never seen on the Arbiter's mission. They are a older model and were slower and not as powerful as later models of the Ghost.