Avan
Well the sword was given to the kingdom by the Fey. More than likely the blessing from the sword was what the Fey intended to give to humanity to make them stronger, but to pull the sword from the stone I think one has to be of Fey lineage. Also the high priestess had visions of Emery and the sword, probably meaning he was destined for it. On top of that, with him being alone in the tunnel and the chapter title being called, "Chosen One". It's more than likely Emery, who draws out the sword.