There's a part of the story where demons are negotiating peace between a town and attacking demon forces. As soon as Frieren hears of this, she says the town is doomed.
Moral of the story is if your problems are caused by a group, don't expect a member of that same group to help you solve that problem.
FAR UNDER HALF. NEXT QUESTION.
Muslims owned & traded far more slaves than Europeans ever did. In fact Muslims took more (White) Europeans as slaves than the Europeans (combined, including Americans) ever took from Africa or anywhere else.