Im not so sure, according to Alduin's Wall(The far left panel) the Avaviri Dragonguard fought right alongside the Ancient Nord Heros against Alduin and his men during the Dragon War. Since Alduin at that time ruled over everything...not just Skyrim or Tamriel....I think its safe to say the Avaviri were the first to rebel against the Dragons(or Alduin and his dragons invadved Akavir but met severe resistance from the Avaviri and were forced to abandon the plan when the Nords rebelled)....However, when Skyrim decided to rebel against Alduin's rule, Alduin turned his attention from Akavir and wanted to qwell the rebellion in skyrim....however the Akaviri Dragon guard followed Alduin to Skyrim....its plausible...afterall, it wasn't discovered until many years later that the Vikings traveled and discovered north American before columbus did. It wasn't like the Blades just allowed anyone into Sky Haven Temple...and they spent considerabel resources creating Alduin Wall (which portrays the blades history from the Dragon war to present dayShowing the Avaviri Dragon Guard supporting the Nord Heros) The Avaviri either used Dragonbane against the Dragons, or lent it to a Nord Hero whom they considered worthy(most likely a Dragonborn Hero). also, The Avaviri DragonGuard may have helped train the Ancient nords how to kill these Dragons as they were experts at this, The Nords had no prior expereince fighting them and fighting them is different then just fighting men.
Alduin recognizes Dragonbane because its probably the one weapon wielded against him that actually really hurt him....it was different from other weapons...its secrects are still not fully understood....the weapon has a mysterious past, we know its an Akaviri artifact, we know its very old because Alduin recognizes it, were not sure exactly how it was created....was it created by magic? perhaps one of the divines blessed a weapon of the Avakrir Dragonguard? we may never know.
On a side note, its too bad Alduin never had a showdown with Pelinal Whitestrake(The Divine Crusader), he wielded the weapons given to him by the Eight Divines before Talos Ascended, the Mace of Stendarr, the Boots of Kyne, etc...I wonder if the Divine Crusadrer would have been able to do battle with Alduin and hurt him with weapons forged by the Divines themselves....I wonder if The Divine Crusader would have even needed Dragonrend...I would think those weapons he had forged by the Divines themselves would be able to hurt Alduin one would think...as they were not created by mortal or daedric hands...