Not sure if rembered, but Reilsss orginal background story was mostly about surival in a dragon war. (I'm kind of glad that I moved away from that background to a more frindly one by now)
The image here illustrates what Reilsss would look like in heavy armor. His weapons of preference are big swords. But don't get misstaken by their size. He wields them like samurai swords.
And why does he not have a helmed? Well rember that Reilsss is a fire element based dragon? If he where wearing a metal helmed it would melt if he used his fire breath element. And that one is heavily wired into his combat style.
(His fire element is also reason why he would not take damage from this kind of firely enviroment).