A: "Brandon had been a fan for a long time before he got to find out who killed Asmodean. He said that he had heard arguments for every possible suspect, including the really crazy ones like Tam. So when he found out the real answer, he wasn’t shocked. His reaction was more 'Oh, those guys were right'. He said that the clues are there, but he never would have figured it out himself."

That's pretty much Graendal if you ask me. Most readers will be shocked to find out its Slayer. It's as likely as finding out Moiraine did it.