Something is wrong somewhere.
1. Akatosh "created" the "Dragonborn" to protect the world. Essentially given them the power to bock Daedra(for the most part) form the world.
2. If Akatosh is Alduin, then Akatatosh created something to protect the world until he could destroy it?
3. If Alduin IS Akatosh, and the Elder Scrolls told of Akataosh coming to destroy the world, then Akatosh creaded that which will defeat him.
1. It wasn't Akatosh who willingly did the Amulet of Kings.
The legend says that in 1E266, Shezarr (also known as Lorkhan), the missing sibling god of the Eight Divines, transformed the dying Empress Alessia into the first of the Cyrodiilic saints, and bound her soul into the Amulet of Kings, after which the amulet became a heirloom of the Cyrodiilic Empire.
The Amulet of Kings, formed when Akatosh infused Alessia with his own divine blood, then had Shezarr place her soul into the newly formed Amulet of Kings. Alessia's soul was bound to the Amulet, as Akatosh vowed: as long as an heir of his and Alessia's joined blood sat on the throne of Cyrodiil, and wore the Amulet of Kings, the seal will remain in place and Tamriel would be safe from the Daedra of Oblivion. As a sign of this vow, Akatosh lit the Dragonfires in the center of White Gold Tower.
This presented a means to bind all dragons to the service of the empire, and to use their power to maintain the Dragonfires;
the price was placing Akatosh at the head of the human pantheon and strengthening him through collective belief.The destruction of the Amulet of Kings effectively terminated this pact on both ends.