So what metal is the guy wearing? You have to think about this type of stuff when your modeling and skinning him. If's its a non-reflective metal, is it strong enough to keep him well protected?
As far as the skin goes, it looks very flat due to the dark black lines near the end of the armor pieces, blend that line in more. Also I cant find a lighting source anywhere on the skin, that helps if you want to make it "pop" out a lot more. Add more dirt and damage too, to fill in the empty space.The muscles in the arm seem too defined, the outlining color is way too dark.