Ok but Lambert shaders dont have a spec component.... so I'm confused. I also noticed that his trousers have a very well defined highlight, as do the rocks these two materials should be very diffuse and not reflect or give highlights... I would tweak your materials. Even if it means repainting.
So did you paint in the spec highlights? cause that's not a great idea. I dont mean to be rude but I think you've got a well modelled character that is being let down by the materials
Technical Director - Framestore
Currently working on: Your Highness