User blog comment:WillofOP/Random thoughts part 2/@comment-4493594-20111122224932/@comment-4493594-20111123003201

While Zoro has certainly a strong will and probably also a strong soul he doesn't have free control over his soul like Brook. I don't think the sword has anything to do with it. It's just a piece of metal, maybe with some spiritual mumbo-jumbo on it. But still, I doubt it will work on Zoro.