Pretty good piece! The armour is godly detailed, the lightning effects are strong. (From both the fire from the door, and the moonlight above.)
The head seems a little out of proportion, but not by much.
The feeling of the drawing is generally pretty solid, I imagine him walking away from his friend/wife on his way to duty, looking sternly ahead.
I would perhaps have enjoyed to see him look back instead, but all in all, this is a very good drawing.