The build up to Graendal from Lews Therin's point of view is based on the riddle, 'how do you beat someone who is cleverer than you on every level'? No one could answer him, and Lews Therin had no idea how to defeat her - but he had ways to defeat Lanfear, Sammael and other Chosen. To him, she was the supreme puzzle.

Rand derives the answer 'let her think you're playing her game then punch her in the face'. He balefired the entire palace. It was instant, unpredictable and total - she didn't have a chance.

If Graendal survived it will make Rand seem like a fool because even though he derived the answer, he failed. It doesn't make sense. Cadsuane had to work out how to break Semirhage, and Rand had to work out how to defeat a mind manipulator. They both succeeded.

The reversal of the Compulsion was specifically inserted to show that she'd died. It strains credibility to think that she'd perfected that timing, while at the same time she had to avoid the biggest blast of balefire since the War of Power. She also had no way to know that Rand would use balefire, so why would she create the 'unweaving' subterfuge. Rand might have used a giant fireball or swallowed the palace into the earth. If the Compulsion had unravelled then, she would have looked really stupid. Graendal cannot be as omniscient as others are portraying - she merely had the ability to invoke an atrocity because she couldn't be defeated in other ways.