Very, very neat indeed.
I don't think you were unsuccessful with the helmet, I believe that others think you could improve upon it... Though I can't seem to think of any ideas to help you. Humph. I shall edit this post if I think of any!
I do think he's a pretty neat fig. Did you use a headlight brick or a 1x1 with an axle hole and a half pin connecter to fix the shield to the body?
Weapon wise, I think maybe you could make a wooden spear. It might look a bit more proportionate to the fig rather than the halberd.
Great MOC, I await to see what improvements you could make on this, as well as other MOCs!
Chewie