The mysterious orb is an item obtained from Veos during the Client of Kourend quest. It must be taken to the Dark Altar to be activated.
Once the orb is activated near the Dark Altar, it will shatter into broken glass. If a player activates the orb anywhere else, a message appears stating that the orb is unresponsive.
It is possible to obtain a duplicates by banking and having none in one's inventory, but upon the task being completed and completing the last dialogue with Veos, the duplicate will be removed from one's inventory or bank.