The most obvious weave existing after the channelers died is the weave that shielded Callandor from everyone except the Dragon Reborn. That lasted for 3000 years which is way beyond the lifespan of a channeler. I also have a vague memory of RJ confirming that tied off weaves last forever, but I am too lazy to look it up right now.



This has been debated about a lot, but unless there is some hidden trickery then yes, balefire was responsible.

Infact the point was that Graendals compulsion causes severe brain damage and even after its unraveled its effects remain to some extent (which is why that boy died after Nynaeve unraveled the compulsion). By using balefire to kill Graendal, Rand made it so the weave was never made in the first place so there was no compulsion and also no residual damage. That is how he knew that Graendal was dead.