The writing in this game tends to go for grandeur rather than logic.
Tadpole weakening the subjects does not make sense. Why would they want their mind controlled true souls weakened? How would powerless slaves ever be worth the effort? Minthara and Ragzlin are not level 1.
Also, companions who boast and complain about having been really powerful, when they are in fact casting 1d10 Fire Bolt at goblins, are not very likable. Never liked that Gale introduction scene where a level 1 Wizard pretends to be all that. Even if he actually was a powerful Wizard who lost his power, the scene is poor. He was abducted, lost his power, tadpoled, ship crashed into wilderness from Hell, alone, level 1, Mind Flayers around yet he's entirely casual and seems to be in a good mood.