As demonstrated in TGS... - Edit 1
Before modification by Nameless Ashaman at 12/08/2010 05:32:51 PM
But he needed Semirhage to remove the vestiges of the weave, thus implying that while he can recognize when a weave has been placed or even what it does, he cannot nullify the same weave.
Removing compulsion without destroying the victim's mind is a subtle and tricky operation. Semirhage would probably be among the best to try it. If SH somehow removed the compulsion by simply nullifying the source (assuming he can do that), it may have left Elza useless for anything else.
This doesn't prove SH broke Cadsuane's wards as we don't know that he can affect existing weaves, but it does keep the possibility open.