I dont believe rescue is in the question -- you'll have to go thru a bunch of Ashaman and Aes Sedai as well as the Dragon Reborn to get to her, if they could do that they would have killed Rand himself by now. As for killing Semirhage, again who is going to do that unless its from her dreams? Anyone who bonded her she would probably manipulate with/without the Power.

 

Better for Rand and company to sever her (they can heal her back if needed) or put the adam on her and keep her restricted from anyone but Cadsuane and Nynaeve, even send her to Sorilea and the Wise Ones. If Semirhange, Mesana and Demandred did not plan this between the 3 of them.. I can see Semirhage allowing herself to be captured in a way where they think she is subdued.

I don't... her plan to capture Rand would have worked without the ter'angreal.

 

The person who bonded her need merely command that she work only toward the victory of the light. Or command her not to do anything to cause dissention amongst people.

 

I agree it would have to be someone intelligent and strong-willed, but controlling Semirhage would not be that hard with the bond.