It's not very clear if what is "inside" is concave (hollow) or convex, but that doesn't hurt the general impression.
The armor outline is precise, it shows you know what is the 3D shape of the character parts. With this knowledge you could have marked the direction of the light source much more. I mean, you do it for the top-bottom (outside light is clearly coming from above), but surfaces that face left, right, and toward the viewer : they are equally illuminated.
Hmm... Now that you mention it. The confusion about the concave aspect is true. However, I'm unclear on what you mean by the light sources. Thanks for your observations and critique though. Much appreciated.