5 Episode 2 ~upd~ - Merlin Season

He grips the hilt of his sword, Excalibur, the weight of the crown heavier than ever before.

Merlin is losing hope. He sees Mordred alive, trusted, and heroic. He sees Arthur stubbornly kind. He sees the prophecy tightening like a noose. Finna's death reminds him: he is alone. No one else knows the weight. And the "golden age" keeps slipping further away.

Kilgharrah's cold reply: "Then you must do what you have always done. Carry on." merlin season 5 episode 2

In the end, Merlin and Arthur manage to defeat Eriol and recover the diamond. However, not before Arthur realizes that his deepest desires are not weaknesses, but strengths, and that he must learn to control them in order to become the great king he is destined to be.

By the time the credits roll, the status quo has changed forever. Camelot feels stronger than ever with its new knight, but the shadow of the prophecy has never been darker. He grips the hilt of his sword, Excalibur,

(Telepathic) The Diamair... it is not a weapon. It is not a sword. You do not understand what you seek.

But deeper:

I understand that it will bring the Once and Future King to his knees! Tell me where it lies!