Don't know what they used here, personally I'd get Vallejo metal medium and try some mixing with yellow browns, zamesi desert, tau light ochre etc etc. The shadows are almost certainly agrax as a final coat. Personally I'd go zemesi / metal medium 50/50 mix then slowly increase the amount of metal medium or even add white. to build up to silver edge. then give the whole thing a couple of coats of watered agrax to tie the blends together.