It's all horns and spikes and pointy teeth and black and all you need for the scary villain armor. The first thought would be that the armor is supposed to make him look dangerous, but look closer at the helmet. It's designed so Sarevok's face is framed by the helmet's teeth, like a maw that's swallowing him. I really like it, because the first impression you get from the design is that he's a dangerous enemy and that's what Sarevok wants to show, but the second impression you get is that he's not as in control as he thinks. The armor is taking over, the beast is devouring him. When Sarevok dies, his body turns to dust, but the armor stays, leaving him entirely consumed, the taint having won over him. In ToB, on his portrait, Sarevok has a golden armor, and while there were plans for cut content involving restoring the sword of chaos to return it to him, there was never anything for the armor. The armor was the beast he tried be, the beast that ended devouring him instead.