File-D is an extremely powerful weapon invented by the Spirit of the Abyss for use by the Magog. Although it looks like a typical Flexi, it is in fact very sophisticated and dangerous. It can apparently destroy a person's mind and personality, but leaves the body intact and alive, which is then a perfect host for the Magog to implant with their young.
The New Systems Commonwealth retrieved the weapon from an uninhabited world, but it went off while it was still being transported after it was attacked by Magog, rendering the entire crew of the Magellan Melrow catatonic. However Calleb Voth from the Rakshasha Pride discovered the drifting ship, boarded the Melrow, and managed to retrieve it before the nearest Commonwealth ship, the Andromeda Ascendant, could get to it. The crew of the Andromeda, however, managed to trace it to a militant Nietzschean camp, and got Seamus Harper aboard the vessel being used to store and transport it. While he was aboard, the automated ship lifted off, and since it was equipped with finely tuned gravity generators, Harper did not notice the takeoff. While repairing it, he accidentally armed it, but managed to defuse it and turned it over to Andromeda. It was then put into storage. ("Harper/Delete")