Consider the following scenario:

Idiot emissary arrives. Graendal Compels him, using her angreal because the Compulsion needed to be strong/delicate/etc., and sends him back to Rand, as Rand predicted. However, the emissary's arrival makes Graendal very nervous. She considers that her position has been compromised, and so prepares to Travel out of there at a moment's notice (first ensuring all the inverted Wards around her mansion, which almost certainly existed, are in place). Sometime later, Rand arrives and triggers one of the Wards. In the meantime, Graendal has put down her angreal somewhere. So, when the Ward is triggered, she doesn't have it with her, and doesn't dare take the time to retrieve it before Traveling out of there. Which she does. Rand then balefires the mansion, and (amongst other things) destroys the angreal. But Graendal escapes.

I'm pretty sure that, in that scenario, the emissary's Compulsion would be erased, since the angreal was used to weave it, and the balefire made the angreal cease to exist before it was used. I'm not 100% sure about that, though.