I textured this piece for the Cinematic Texturing Class at CGMA awhile ago. The the model was provided by the class instructor Chris Nichols.
The high frequency details was done with Zbrush with custom alphas and for the skin textures I projected in Mari from images and then hand painted different layers of face-paint, dirt, scars and scabs for the head, shirt and jacket.
The rest of the metal pieces I painted in Substance Painter. and rendered everything in Vray