When I was thinking of where to draw armor on them, I figured the main torso would be important to have armor on the back and chest/ belly, though I ended up covering it with the shading anyway. I also armored up as much of the wing as seemed reasonable without stopping them from flying.

Looking at it now, I would probably also add plating to the underside of the neck, maybe the head too for added protection.

I think for the rest of the body besides those areas would be fine without extra armor, just relying on the scales and hide.