Reins of the Blue Drake

Source
This item has an extremely low (1% - 2%) chance to be found inside Alexstrasza's Gift after defeating Malygos in the 10-player version of The Eye of Eternity.

This item also has an extremely low (6%) chance to be found inside the Cache of the Ley-Guardian, which can be found in the Cache of Eregos after defeating Eregos in the Oculus on Heroic mode when the dungeon is randomly selected by the Dungeon Finder.

This item also drops from Satchel of Exotic Mysteries