Omega Arsenal

The Omega Arsenal was a collection of forbidden weapons locked in the Time Vaults on Gallifrey. (TV: The Day of the Doctor) The Tear of Isha was kept in the Arsenal, (PROSE: Engines of War) as was a weapon capable of generating a Null Zone. (AUDIO: The Heart of the Battle) Over the course of the Last Great Time War, the Time Lords used all the weapons in the Arsenal against the Daleks except for one: the Moment. This was stolen by the War Doctor in the final day of the War. (TV: The Day of the Doctor)

Behind the scenes
The "Fourth Dimension" feature on the BBC's Doctor Who website suggests that the Omega Arsenal is a reference to Omega.