She's been on battlefields and seen death so many times that the actual act of seeing the dead isn't really surprising to her, especially knowing what demons intend to do and are capable of now, I figure; her methods of looking through the village are precise and accurate, the sort of thing a soldier might do to trace enemy involvement in an area.
It's another case of the world's Heroes having a different standard of morals versus her own, given it seems this one is extreme enough to try to kill people for thinking they may be in a demon's control with flimsy proof.