I know of a darkside glitch, but you must have handmaiden and still be sparring with her. It basically involves begining the sparring session, then ending it prematurely (put on clothes or use a weapon etc.) then when you get the conversation dialogs, make sure you choose the nastiest dialogue (I cant remember the exact order, but its just picking the cruelest lines and insulting her, and make sure its her who ends the conversation). when thats finished, you should get some DS points, and be able to restart that sparring session with her again. (it will take time to get to fully DS )