Supply Bag

The Supply Bag was a unique 18-slot bag given as a quest reward.

Source
The quests were given by Quartermaster Miranda Breechlock. She had a Quest for each tier of faction (Friendly, Honored, Revered and Exalted). It required a turn-in of a large number of Insignias of the Dawn and Crusade. (See Armaments of the Dawn for summary) The Quests were:
 * Superior Armaments of Battle - Friendly with Argent Dawn - 30 Insignia of the Dawn and 30 Insignia of the Crusade
 * Superior Armaments of Battle - Honored with Argent Dawn - 20 Insignia of the Dawn and 20 Insignia of the Crusade
 * Superior Armaments of Battle - Revered with Argent Dawn - 7 Insignia of the Dawn and 7 Insignia of the Crusade
 * Superior Armaments of Battle - Exalted with Argent Dawn - 6 Insignia of the Dawn and 6 Insignia of the Crusade