Except he isn't well written. Sarevok is, while Irenicus is a cartoon moustache twirling villian. For example, Irenicus is written as a genius, yet his intelligence is presented only by his prowess in magic. Many of his actions and decisions are pretty dumb (from secret underground laboratory in a city where magic is illegal while he has no political clout and it gets invaded by common thieves, he also had full control over PC twice and both times he let the PC slip like a total buffoon, all that while being a genius level wizard) and he relies on plot armor and plot powers to stay relevant. Sarevok on the other hand isn't written as an incredible genius with superpowers, yet we actually feel that he is smart and cunning with the way he manages to scheme and manipulate events on the Sword Coast.
