I think it has been said/speculated that he has a greater hold over those who have sworn to the DO. So he might not be able to cancel the weaves of someone who is not loyal to him. He is able to physically hurt someone who cannot fight back like Mesaana however.



I think the argument could be made that its not exactly failure that pisses the DO off. I mean given that the wheel has apparently been turning for a long time, and that the DO has failed to win in each turning, it makes sense that he might be more understanding than the average evil overlord about failure. Sometimes you just cannot win, not even every time.

That is why Balthamel and Aginor were not horribly punished, sure they failed miserably and I expect the DO might have slapped his hand to his forehead in despair once he saw how, but they also showed no sign of actually being disloyal. Ishamael too got his ass kicked and failed, but once more he was loyal to the DO until the very end.

The crimes of Moghedien and Mesaana are worse than just failure and incompetence. They actually betrayed the DO. In the case of Mesaana, the betrayal was one of knowing disobedience. In the case of Moghedien, she willingly and knowingly supported and taught the DO's enemies.

If Moghedien had escaped by channeling the TP or killing herself or something, I expect the DO would have been more understanding and saved/protected her.

Likewise if Mesaana had come to the cleansing and been vaporized by a blast from Callandor, the DO would have captured her soul and saved her.

But their true crime was one of betrayal/disobedience which is why their punishment was also worse. I expect if Asmodean had been captured alive, he too would have enjoyed some quality time with SH too before being mindtrapped.