Although this is impressive work, I don't think it is your best. The minimal black white and red color palette without shading gets the point across, but I think the faces could have really used some more definition. It's still a great idea and a good work of art, but I feel that the lack of details are hurting it more than helping it.
The black textures are kinda clashing. I feel as if you should have used solid black and faceted it instead so as to help give an idea of depth.
One of your stranger works, but the more I look at it the more I like it. Well done but could have been better.
The critique hit the nail on the head with this one. I think the guard in the back is fine, but the guard in the front needs more... something. Maybe the right side needs to be filled black or cropped out.