I'm sure people have thought about this before, but I just read a part of Gathering Storm where Tuon is musing on whether an Aes Sedai could be forced to use the One Power as a weapon.
The third oath is: "Never to use the One Power as a weapon except against Darkfriends or Shadowspawn, or in the last extreme defense of her life, the life of her Warder, or another Aes Sedai"
Obviously they can be forced-- one way is by forcing them, their warder, or another Aes Sedai forward into danger from an enemy and then coercing them like any other enslaved channeler.
But is there an easier way?
Is a knife to the throat and a threat to kill them if they don't attack with the one power "the last extreme defense of her life?" Obviously the slavers would be reluctant to do this because they don't want to kill their slaves, but would it be effective?
At one point in the early books (unless this is a show-only scene and I got confused) Egwene is unable to pick up a pitcher because she thought of it as a weapon. Could a similar trick be used, such that an Aes Sedai who has been enslaved is tortured or brainwashed until she believes anyone who doesn't serve the Seanchan Empire is a darkfriend, thereby enabling her to use the power as a weapon almost indiscriminately?