The character's pose would not have been possible without proper use of shading, and you did it so well here with proper attention to your light source. Each way that you chose to use lights and darks on the armor displays the beautiful detail in each piece (for example, the smaller skulls hanging off his belt would not have been as noticeable had they been against a lighter background. The glow of the sword against the armor is also very believable.
The character design really is creative. I like the theme of skulls, and especially commend you for working them into the actual armor (my favorite is the one on the shoulder). There really is a very menacing feeling emanating from this picture! Great work!