I don't know how I missed it, but I clearly did and I don't have the book in front of me to find it... When did Rand find the song?? How on Earth did I miss this??? Can someone refresh my memory please?
When Egwene uses this same weave on a much smaller scale earlier on to fill in the cracks that appear in the ground, this was a hint to me that somehow it would be used to counter the effects of balefire. I didn't know on what scale, and definitely didn't know Egwene would die as a result, but...