Quote Originally Posted by Sir Bahamut View Post
Obviously they weren't trying to stop sorceresses in general, but they probably thought it would be better if no one inherited Adel's powers, because of how extremely powerful they were. Thus it would make perfect sense to keep her alive indefinitely assuming that they couldn't kill her without the powers being passed on.
Adel had spent quite some time, and started more than a few armed conflicts, in her attempt to find a successor - clearly, she wanted a successor who'd be as powerful and iron-fisted as herself. I guess the notion of 'power corrupts' applies: her powers corrupted her mind and body into something monstrous, so the same would likely happen to whoever inherited those powers, if they were led in the right direction. It'd be a wise and logical move to thwart Adel's greatest wish by preventing her passing on her powers.