Two Watchers were killed. Whodunit?

As Cinder, oldest and wisest of the Fae, I found Oberon was distracted, Titania flighty, and the soulless Vampyrs everywhere. Puck was causing mischief with Arthur, and by the time I had an eye on him, Watcher #3 was killed. I tasked Puck and his sister Nineve with protecting the other Watchers, keeping the latter safe, the former [mostly] out of trouble, and working together we secured one of the weapons: a wand. Then a Vampyr keeled over: but a few minutes later he was up and about again. Still, since too many knew about the wand, I secretly entrusted it to the Fae assassin, Bounty, with orders to use it only by command of myself or Lord Oberon, who was the only other I told. Unfortunately, I then discovered the reason for Oberon’s distraction: a preoccupation over a vendetta with Merlin over his harassment of Nineve. It was a risk, but I took the wand back for myself, not sure if Oberon’s judgment would be unbiased enough.

Investigations indicated that the Court held a murderer. A Watcher’s spell cleared Morganna. A Vampyress tried to manipulate me against Guinevere, but it was clear she was innocent. I cornered Arthur alone in a back hallway, and brandishing the wand, compelled him to tell me what he knew; it was clear the lad was rash, but no murderer. With time almost up, and for Oberon’s sake- I returned the wand to Bounty, and unleashed her on the last possibilitiy: Merlin.

My crime was hardly concealable: even if the manner of Bounty weren’t known and Oberon’s motive not public knowledge, the Vampyress, Arthur, and the Watchers all knew that I had murder weapon, and my alibi wouldn’t stand up. So be it.

The Inquisitor revealed the truth. I had killed Merlin. Merlin had killed one of the Watchers- but only one, the third victim. For Merlin had deduced that that Watcher had gone rogue, and in fact the murderer of the first 2 slain Watchers!