That quote directly implies that Be'lal knew BF was coming before it actually happened, which is rather odd.

Men cannot see saidar weaves right? Women cannot see saidin weaves right? I know they can sense weaves coming at them, as Lanfear was able to slice Rand's weaves and he hers, but that was after they were formed and moving. From memory I can't recall anymore specifics, but I'm sure there is some. I've always found it kind of odd actually.

Be'lal, and apparently Asmo as well, were able to know it was BF before the weave actually was formed. And of course, Be'lal must be an idiot because if he was able to recognize the weave being formed by some strange phenomenon, why didn't he simply slice it as has been shown to be possible in many other occasions?

This I find weird. Perhaps a continuity mistake? Or perhaps I'm forgetting some small detail that makes it clear.