I think you fail on the prespective of the arm. if the arm is so perpendicular to the light of sight, then maybe we should see a bit of the elbow. also the sword messes up the prespective, because the handle has a normal size and prespective, but the blade looks in prespective, plus it's short. so it looks like its going away from the viewer. only samurai swords are a bit more bend, specially ig you see them from that angle, you can really tell they are bent.
and finally, I cant really see how he is holding it. are the fingers pointing down, or up? is the thumb over or under the handle?
take care,
Kazuya