Hark, I have to say I really like the concept of your Samurai. The colors seem a little subdued to me though, maybe brighten them up a bit. And this is me nitpicking, but... maybe try to make him seem like he has more of a physical form around his torso and head? Don't get me wrong, it looks really badass, but as others have pointed out, it makes him seem more ghost-typed than dark.