Dropping the weave herself wouldn't work- there's the timing issue, first of all, and second, that would have left a residue.

"Dissipating within an hour" doesn't work, because the timing was so exact- there before balefire, completely gone afterward.

Having another woman do it would require 1.Graendal finding someone powerful and skilled enough, someone we've never met or even had a hint existed, to do the subtle Compulsion that was performed 2. Trusting that person to give them such a valuable tool and 3. Delegating the job of Compelling such an important target (arch enemy's messenger to her private stronghold) to an... apprentice! Oh, and then 4. Leaving her palace as soon as she gave those orders.


...yeah