What does the experience of being a merlin teach Arthur about self-reliance, might, and right in The Once and Future King?

Arthur learns that might is not right and that he must rely on his brains—not his physical strength—to survive as a merlin among the birds.
Arthur recognizes that the birds have a strict sense of military ranking and aristocratic hierarchy among them when he joins their ranks. They are a militaristic, bloodthirsty, rigid, and dangerous group to be among, if not too bright. In fact, they are a parody of the British upper classes who ruled the Empire in the nineteenth and early twentieth century.
They sing a song that expresses their worldview: "Life is blood, shed and offered."
Although Wart doesn't want this, they force him to face an "ordeal" to show his worth. They insist he stand beside the crazed and bloodthirsty hawk Colonel Cully, who will feel compelled to kill him if he can. As Wart copes with this ordeal, he realizes he must use his wits to survive, so he tricks and distracts the Colonel:

"There is a cat behind you," said the Wart calmly, "or a pine-marten. Look."

This ruse works, and Wart lives. He also learns he has the stuff of kings, though he does not really absorb this truth yet:

Mark my words," cried the beautiful Balan, "we shall have a regular king in that young candidate."

Wart says of the birds: "What a horrible, grand crew!"