Overall your shading and color selection is quite good, and for the most part, your lighting is fairly consistent (there are a few problem spots such as the character's right bicep). Your excellent shading is where your greatest strength is in this piece, but it seems you've not payed much mind to weather you want to keep the lines or not. There are a number of sketchy areas where decidedly less than final-stage line-work shines through your shading (especially on the sword and armor) as it does in other areas across the piece while in other areas -such as the chest, abdomen, and genitalia- your shading hides/removes the line-work almost entirely. This inconsistency detracts from the piece as a whole. I think removing some of your sketch layer to clean this up would be of benefit. You should also consider going over top of this with a multiply layer and cleaner black (or better-yet, a normal blending layer with appropriately colored) lines- as this would benefit the overall composition considerably. Alternatively you may choose to expand your shading to cover all areas where lines bleed through and use harder edges and your shading to define the shapes instead of using visible lines at all- in a manner similar to what Jason Engle does.
With your inconsistent lines being your greatest weakness in this picture- the only other thing I see that screams 'fix me' is the fact that your edge-light appears somewhat inconsistent and you may wish to review it's source and where you think it might cast additional 'glow' as right now it doesn't seem to follow the contours of your shapes as much as it follows just the outer-edge of the figure as a whole. Changing this should help give the figure more depth.
Overall it's very good work, and with a little more polish it could easily be great work. Just my two cents. Hope it helps and keep up the good work =^_^=
