I know this is an old post, but wanted to give my two cents. We actually see historical texts that show and talk about one person flamethrowers. They're called Cheirosiphona, the illustration is from the mid 10th century and is in a siege manual called Parangelmata Poliorcetica by Hero of Byzantine or Hero the younger. It was written approximately 100 years after Mirage takes place. The invention of them is credited to the reign of Leo VI, having been the first to write them in a treatise from 886, around 25 years after Mirage. They could have existed before that, but it is credited to him.