Black & White really works well here. I think its a good choice as it seems to blot out anything that might be distracting and focuses on the action of the image.
Focus is excellent as is the composition in general. Border is unobtrusive and works very nicely. Fits the challenge perfectly.
My only complaint is the blown out whites of the snow, on the knife and the stick. The snow isn't too bad as it kind of gives a background and isn't hugely noticeable, but the knife and the point of the stick lose detail with the shine of the light on them and that detracts a bit from the image.
Overall however it is a strong photograph and I like it very much. I gave it a 7 despite the white issue.