I think it is that it sounds kinda cool to buy an amulet with an astral sex slave bound to it . I am not sure about the karma of buying an amulet with a real soul attached to it . I guess you would want to set her free and see if she would come back . I dont really think you can force any one to stay with an object . I think a few people do chose to haunt an object tho. Like the doll George Nory discussed on coast to coast , or the dybbuk box from the movie.
http://en.wikipedia.org/wiki/Dibbuk_box