Arthur's Sword by Sophie McKenzie
Arthur is a better sword fighter than his foster brother, Kay, but he's not the one training to be a knight. So he is thrilled to meet Merlin, who promises to help him become Kay's squire. Then the king dies, and Arthur gets the chance to carry out his first big challenge. There's a sword stuck in a rock, and no one can pull it free...Arthur's Sword is a modern retelling of the classic legend of old.