From my understanding of the shout it would seem as the Dragonborn can control anyone or anything with a simple shout. Am I wrong to assume that with the Bend Will shout the Dragonborn can do amazing things like use the shout to proclaim himself Emperor of Tamriel/Highking of Skyrim, use the shout to force kings/leaders of independent nations (Morrowind, Hammerfell, Black Marsh, Elsweyr, or even the Aldmeri Dominion) to accept annexation back into the Empire of Tamriel.
The Bend Will should makes the Dragonborn god.
Tiber Septim needed the Numidian. Dragonborn could have entire foreign armies defect to him at a whim with a simple shout if he could not gain an audience with the leader of a nation to simply shout and force a peaceful annexation.