Royal Ring

"You have to take this. It bears the royal seal. In my absence, responsibility to the kingdom rests with you."

- Arthur to Agravaine

The Royal Seal is a ring that bears the Pendragon seal. It is owned by a king or someone else who is responsible for the kingdom of Camelot. Arthur left the ring with Agravaine when he went with Merlin and the Knights of the Round Table to Isle of the Blessed. It meant that Agravaine had the responsibility to rule the kingdom and that he would assume the throne if Uther should die. This act demonstrated how much Arthur trusted his uncle (The Darkest Hour).

Before his death, Arthur sends the Royal seal to Guinevere with Gaius. After he gives it to her, she has the right to rule Camelot on her own (The Diamond of the Day).

Trivia

 * It can be noted that Uther never wore the royal seal but it is assumed that Arthur wears it when needed.
 * The Royal seal used in The Diamond of the Day is noticeably different than the one used in The Darkest Hour.