Loki's glowing staff has been spotted at Comic-Con! This isn't a replica, but rather the actual prop that was used on set of not The Avengers, but Avengers: Age of Ultron. Take a look:
Comic Book Movie reports:
Loki's staff (given to him by Thanos) played a major role in The Avengers and was seen being utilised by Baron von Strucker in Captain America: The Winter Soldier's mid-credits scene. It's widely believed that he uses it to give Quicksilver and the Scarlet Witch their powers in Avengers: Age of Ultron, and whether this device is related to that remains to be seen.
While I have no evidence to conclude that Thanos gave him the staff or that Scarlet Witch & Quicksilver got their powers from the staff, these are both interesting theories. However, one fan theory that has run rather rampant to the point that many people believe it as fact is that the glowing rock within Loki's staff is actually yet another Infinity Stone, which after gathering all 6 of them, grant you invincible powers. Currently, there are 3 known Infinity Stones in the MCU (the tesseract, the aether, and the orb), while some predict that Thanos may already be in possession of one (with a Purple aura), that Loki's staff has one (with a blue aura), and that Ultron might be powered by one (with a red aura).
What do you predict about the locations and appearances of the highly teased Infinity Stones, which have been all but confirmed to be united by a certain Mad Titan in Avengers 3?