pfah!
I had no impression that Serwe was going to sing sorcery.
but if she were, poison pin obviously refers to a good old "Math Thesis Point" from the False Sun, and since both the glamour about Golgotteranth and the Agonic Collar were both wrought by Emilidis, and both probably work on similar principles of deflection/redirection (which is why it has to be a circle, an Agonic Collar or an ouroborian circle) then therefore a maththesis point (a poison pin, a key!) directed at the collar ought to disable it just as the glamour was disabled.
So that's how she can probably get out collar if need be, most sorcerors either direct sorcery outward (which just causes them to always miss and hit themselves) or at the collar itself (which likewise just always misses and hits themselves) but a maththesis point would not be able to be redirected.
Kellhus would have derived such a solution because he'd want to know how to get out of one as well.
But I think Hirtius is right and it is going to be 'mundane' singing that turns the court against itself.
On the other hand. The chorae theory could be correct,
"it bounced across the grill immediately before her, clattered through a wagging grove directly toward her face, oblivion promising oblivion. A Concussion wracked the platform, and, somewhere, an anchor snapped, and the whole dropped, tilted to her left. The Chorae chipped to a halt a mere cubit from her face. She followed the fingers clasped about the emptiness of the thing and saw Sorweel, his face blodded for flayed skin, his blue eyes fluttering as he strained to focus upon her..."
It sounds like the ending of the Momemn chapter, the chorae was meant to kill Serwe, just as the Yatwerian sent chorae falling out of the ceiling of the andiamine heights were meant for kellhus. In the WLW version of the momemn scene, Yatwer even blinks the tears-of-god into existence herself, casting them at Kellhus. Given Yatwer is having all of the Anasurimbor children killed, I imagine the appearance of the chorae is like the appearance of the stork (twice?thrice) in Ishterebinth, direct intervention of the God. What happens here is that Sorweel has rejected Yatwere, and he reaches out and catches and stops the chorae from rolling and hitting Serwa,