I very much dislike Caddy's character myself. That scene impressed me however, as I think it was quite a humbling experience for Cadsuane. Consider that she had to realize that this vile creature, probably the forsaken whose name would most often be used to incite fear, was very like Caddy herself in so very many ways. That alone would put a sinking feeling in Cad's gut, but she had to go further and find a way that would not only break Semhirage, but would, if used break herself as well. She was forced to realize her own faults, and how fragile the image of herself that she has worked on for hundreds of years really is.