Nice work and nice spin.
If that shield is made from foam, you could seal it and repaint it for sure.
I agree that the airbrush is a little over the top, but I wouldnt lose it totally. Did your friend tell you what the base is from? Did he cover a Batman mask perhaps? How about a chin strap? one of those snap clasps and some strap material = less than 5$ USD.
Enjoy the costume...you've definitely got the body for it