So, I was watching a Youtube video about TWOK where spanish streamer Alexelcapo points out to the chapter 57 epigraph, which is this Death Rattle:
"I hold the suckling child in my hands, a knife at his throat, and know that all who live wish me to let the blade slip. Spill its blood upon the ground, over my hands, and with it gain us further breath to draw."
He then says the 'breath' could be refering to BioChromatic Breath.
If this is right, then the POV character of the Rattle is about to kill a newborn to get their Breath. But there are some inconsistencies. We know that normally one can't steal Breath, nor even give it by accident, it has to be given with intent (Intent?), which is something a baby can't do.
So, is it possible that the knife in the Rattle is to be used as a hemalurgic spike? The 'let the blade slip' part could mean 'pierce' instead of 'cut their throat'.
What I imagine is a scenario in which a group is in dire need of magic to survive something that has already killed many, but their only source of Investidure is the Breath of a newborn who, unable to talk, is unable to use it. So the leader of the group faces the desicion of whether or not to take away their Breath through hemalurgy to save the rest.