So I'm going to have to get creative here:
However, these dragons may also be flying due to natural hydrogen sacks in their bodies. Hydrogen is 14 times less dense than air, and if enough is inside its body, it could, in combination with wing power, a dragon
This was shown in the documentary/movie "The Last Dragon" aka "Dragons: A Fantasy Made Real" Look from minutes 17 to 22 in the following link;
However, he has powerful Dragon shouts, powerful magic attacks worthy of Dr. Strange.
The tech
Given this, I have to conclude...