Nice work on the warboss the skin looks great! A tiny suggestion would be to either paint the blue cable on the bosses arm a different colour, or alternatively, find a spot to paint blue on the gun. By doing this you will give the model more 'balance' as the blue cloth and cable stand out from the rest of the model. The technique is called spot painting and the idea is to form a triangle of contrasting colours, like the white on this psyker
http://www.dakkadakka.com/gallery/159048-Primaris%20psyker.html
Hope this helps! Keep up the good work