By "shields" I'm referring to those shields that aren't shields that Shaidar Haran uses to completely block the Chosen's ability. It doesn't feel like shielding, it's like the Source and your ability are completely gone.

Shaidar Haran specifies they've not been severed, so it sounds like Osan'gar couldn't feel Aran'gar's ability either.

Reread the introduction scene of Aran'gar and Osan'gar with Shaidar Haran.

My theory is that what I call "TP shields" for convenience's sake is what is responsible for Cyndane's largely symbolic reduction in strength. I don't see what else than the DO could have reduced her strength by a fairly insignificant percentage (perhaps significant in terms of raw quantity of saidar she can handle, but it's still a small percentage of Lanfear's strength that got lost) like that. Lanfear did what she did because of her obsession for strength, and like Moghedien she would have been thorougly questionned, and couldn't keep much at all back (even Moridin says so, and implies Lanfear used to keep secrets but Cyndane can't). It's a very fitting punishment and a warning, to show her even her strength and her ability to channel the OP at all she keeps because the DO chooses to let his Chosen use the OP instead of forcing them all to give it up for the True Power. The fact the reduction in strength is noticeable but not significant enough to hinder her service to the DO is another clue this may be Shai'tan's doing. So is the fact Cyndane is the only transmigrated Forsaken who isn't allowed to admit who she once was (the others never use their old names, but freely refer to their past. Cyndane doesn't, except in fury and when she does Moridin touches her mindtrap...), not to even think of herself as Lanfear in her POV. That's the other thing she was too proud about: her body and look, her reputation, her name. Unlike all the others, she had chosen her Forsaken name herself and made it flattering, and she very much cherished that - now she's not even allowed to let the others know she was Lanfear. She's been turned into a nobody, the only Chosen the others aren't sure is even from the AOL! This was also the appearance she had used to try to seduce Rand. Combined with the very humiliating name "Last Chance", this all seems to form a whole, and points to a desire from the DO to teach her a lesson, and he did by punishing her where she had sinned. Her love for LTT, her obsession with strength - it's how she ended up betraying Shai'tan.