"Why do you want to learn about it?"

He feels a little like Lan Qiren throwing a scroll at his head; it's a deeply uncomfortable feeling, one that almost lowers his guard another inch. But she has the Ninth, he reminds himself. That can be enough without involving him or Lan Zhan.

And in the end, Moiraine sees her ultimate goal as healing people of the mark of the Shadow. That is not a benign reason to seek out knowledge of necromancy.