D&C 2

Where it was timely for Malachi and the Savior (Americas) to say that Elijah would be sent, in my mind, it became more timely in modern day as Moroni relayed to the Prophet Joseph Smith - "

"...I will reveal unto you the Priesthood, by the hand of Elijah the prophet, before the coming of the great and dreadful day of the Lord.
2 And he shall plant in the hearts of the children the promises made to the fathers, and the hearts of the children shall turn to their fathers.
3 If it were not so, the whole earth would be utterly wasted at his coming."  (Doctrine and Covenants 2:1–3)

Though I admit I do not know the meaning of all things, I believe the words "reveal unto you the Priesthood" would suggest the sealing power, or fullness of the priesthood is priesthood power and authority related to receiving exaltation.