I went more for the high tech bit, rather than the medevil path.
Also, I figure that since he went on a rampage, he was not likely a grunt, so probably a bit up in the ranks at least .. perhaps an officer?
So, I used Tech Bot as a base, changed the face to a full tech helmet, which holds about the only color on the armor(apart from the Jewel on the chest and the cape), thus being the distinguishing feature of possibly his whole unit.
Changed the shoulders too, to some tech ones.
Oh .. and added a cape to show off rank, and a fire axe ... which, I for some reason really like. Maybe he simply grabbed the nearest fireaxe, if he was denied his nice plasma rifle ?
On to the pictures!
posing in the sunset
Front
Front - roar
Front - Axe out
From the side, cape flaring out
I think it's a relatively clean design, and you could probably both use it as a heroic character, and as a villain.
(he's likely a cold 'n' clinical [censored], no wonder he made officer)
Basically, a normally unimpressed and ruthlessly calculating character ... which the odd rampage thrown in.