One design proposal, just for fun.
DEATH knights
Sometimes, in war, you realy need to get close and personal with the enemies. Be it because of cover, or the need to circumvent some defenses, or just intimidation.
This is why we need knights.
Based on our experience with DEATH marines and GREAT robotic troops, the DEATH knight is a bipedal chassing 2 meters and half tall, with significant limb strength for carrying weight and reaching surprising speeds for its bulk.
The defensive systems are threefold:
First of all, the armour: above the sturdy metal frame, there is a thick cover of nanotube reinforced refractory C-C composite, treated to avoid high temperature oxidation. This is believed to help against heat based weapons such as lasers and its charcoal black oclor gives the knights a dark and solemn look.
Secondly, the shield: Each knight mounts a testudo system on its back, with a singular kite plate 1.5 meters long, optimized to defend against the kinetic attacks that the armour is less suited against. A group of knight can link their testudo systems to form a shield wall or, appropriately, the namesake testudo for defense.
Finally, since we observed a prevalence of laser weapons among enemies, a smoke generator was added. An organic compound is oxidized to produce soot and smoke that are then expelled through holes spread across the armour. This creates a covering cloud that obstructs the wavelengths used by enemies, while allowing our own sensors through. It is unknown who decided to add sulphur to the mix, but the smell of brimstone and the occasional sparks and small flames gives the DEATH knights what has been called "an hellish appearence".
The main weapon of the DEATH marine is its sword. A 2 meter Zweinhander, made of mdoern alloys and with a transuranic core providing extra mass, would already be a formidable skull smasher. However the effectiveness of our welders against hiver alphas convinced the design team to add another twist,creating the Arc Blade. Thanks to a suitable pattern of conductors and resistences, electric arcs can be created across the length of the blade, hopping through some small spurs on the blade itself. This, obviously, increases the lethality of the weapon. And that is the only reason why we added that functionality.
Strong, fast, armoured and armed, like the knights of old those black warriors will beat anyone in one on one combat. They are, however, made to be used together with more conventional GREAT regiments, to provide fire support.
They are more autonomous than the standard infantry robots, and the presence of humans in a DEATH knights attachment is reduced to a group of controllers in a mobile command post, aided by an AI in a similar way to how the expedition oeprates its DEATH marines.