When i saw the ‘historic interest’ and ‘runs fast for short distances’ i knew exactly what you needed.
I’m proposing that you slap on some weapons similar to Roman Legionaries, I’m talking Gladius, Scutum and two Pila or some magical alternative. While you’d be less mobile than most OCs, you’d be without a doubt impossible to fight head on due the the fact that a Scutum covers you head to toe and makes it very hard to see where your next attack will come from. If you want to be better suited for faster and magical enemies, maybe give the shield an enchantment that stuns or something or switch it for the Cavalry varient.
Your helmet is already similar to a Roman helmet which also made me think of Romans.

As a special ability, you could have a summonable Cohort of phantom Legionaries to form up as a unit with you so you can overwhelm opponents and becoming much harder to kill for ranged opponents by forming the legendary testudo formation. Maybe have a randomised special unit as a bonus as well like a Ballista, Cavalry or a War Elephant if you wanna get your Carthage game going on. If you wanted to be straight up silly, you could even throw in a batch of flaming pigs to wreak havok on those who can duplicate themself or clone your abilities, sending them into dismay while also looking hilarious.

I’d recommend a change in the colour scheme too, namely the patterns, maybe going from the dog legged alien dude he is now, he could be human legged with heavy armour like Segmentata (classic Roman armour) with a slight modification to the helmet.

I’m not saying make him a legionary however, you can if you want but i reccomend maybe putting a twist on the idea.