Someone with sufficient skill in interrogation couldn't have discovered it, Kerb was Compelled not to tell. As for heraldry, I don't recall what you're talking about. Which leaves us with what I said.



She's one of the Chosen, it's not her place to perform such trivial tasks when she's got numerous servants capable of doing it, just as it's not Demandred's place to fight on the front lines.



Actually, they are. Nynaeve only went because of her conversation with Rand and need to prove her worth. If it hadn't happened, Milisair would have died and nobody would know anything. And Graendal had no way of ensuring this would happen. And it would have to be Nynaeve, only she had the necessary skills to obtain the necessary information.

And it is only through chance worthy of Rand's ta'verenness that Kerb was able to speak Graendal's location after having his Compulsion removed, not something Granedal could have predicted. In fact, read the passage of Nynaeve removing the Compulsion again. To assume that this Compulsion was woven with the intention of being removed to provide a lure is fantastical in the extreme. Graendal would have to predict that someone would be able to do it, which is again highly unlikely.

And of course, there's the attack on Natrin's Barrow itself.