Disclaimer: I have no idea who owns Merlin ©, but I do know that it's not me!
Way 2: A Beheading
Uther growled and gestured to the executioner to step forward. He moved forward and bowed to the king. "Cut the sorcerer down!" Uther ordered. For a moment, Arthur thought that Uther was going to change his mind. He should have known better. "Bring your axe and the block. If the weather will not permit a burning, then we will have a beheading."
Merlin turned green, and he tried to struggle up. Arthur nearly spoke up, but Uther raised a hand to him. "Not a word, Arthur." He warned. "I will not have the Crown Prince of Camelot undermining my authority."
Arthur stopped again, trying hard not to show any emotion, but unable to stop his hands from fisting. He turned back to Merlin as his neck was forced down onto the block that had been brought to the platform. When his neck touched the block, all the struggle went out of him. He slumped, utter hopelessness in his eyes. This was the end. It had to be.
A guard reached the platform with the executioner's axe. The executioner lifted the hefty blade and brought it down towards Merlin's neck. He measured the swing, pulling up just short of Merlin's neck, then brought it back up. A few swings later, he nodded to King Uther. He was ready for the neck stage of the execution. Uther raised his hand, and the executioner raised his axe in perfect synchronization. Uther paused, drawing out the moment. And then his hand dropped.
Arthur forced himself to keep his eyes on Merlin this time. He would metaphorically stay by Merlin's side to the end. The executioner's axe fell and Arthur waited for the end.
The swing missed Merlin's neck by inches.
Instead, it hit the platform, and decided it wanted to stay put. No matter how much the executioner, any of the guards, or a combination of all the guards and the executioner, tugged and pulled, the axe remained embedded into the platform.
And Arthur could happily say that throughout it all, Merlin had not uttered one word of sorcery. Not that he even could, considering the chains on his wrists that made doing magic impossible. But Arthur was now a very pleased witness to the event.
Uther scowled, and Merlin let out a very relieved breath. "Take him to the dungeons!" Uther ordered. "There are other ways we can prepare to dispose of a sorcerer."
Well. Arthur thought as the guards finally gave up on the axe and started leading Merlin away. At least he's been bought another day.