It completely surprised me that Rand would really balefire a whole palace and thus showed that Rand became very unscrupulous in his war against the Shadow. That Rand came up with the idea to prove Graendal's death with balefire & Compulsion was also very clever.

If Nynaeve hadn't find Graendal's spy in time, and if she hadn't successfully dispelled the Compulsion to get the name of Graendal's hiding place, Rand wouldn't have learned where Graendal is. Graendal isn't that stupid, but - like the other Forsaken - she is also far from the genius that some readers consider her to be. Therefore she was outsmarted by Rand.