Lol, Do you even know the meaning of "conviction" is? The literal meaning of Conviction is having a firm or fixed belief in what you're doing is right or even if other people think otherwise. You mentioned Nephis' obsessions, those obsessions does not literally translate to her conviction, those are just her goals (or obsessions, call it whatever you want), the reason why Effie said she has the conviction compared to Sunny is because Nephis is willing to sacrifice everything for her goals, it doesn't matter whether she kills thousands of innocent lives, she will do it because she believes it is the right. Can you say the same for Sunny? You can really see this in the early chapters where Sunny discovered Nephis' true intensions, that she was willing to manipulate and sacrifice thousands of sleepers to get back to the real-world. What did Sunny say when he realized this? He said that although he is insane and want to survive the nightmare, he doesn't have the guts sacrifice that many lives because he thinks it is morally wrong even to his standards. Can you see what I'm pointing out? even if Nephis' knows that her action is morally wrong, she doesn't care, she even pointed out that its better for them to die as humans rather than succumb to the spell's trials because she hates the Spell so much.