Only issue I have, LH, is your ban. Evidentally, I've so far failed to explain what a Ban is supposed to be, lemee give it another shot. Qualifiers for a demonic Ban should be things you might be able to find on the shelves of the metaphorical military Wal-Mart without having to special-order them, but nothing you'd bring on a military sortie without knowing ahead of time that you should be. In this case, like Vergil's succubi having 'weaker than ordinary demons' was basically having no Ban at all (since the effects of a Ban are to injure/weaken the demons), having "enchanted dragon-bane weapons forged from the bones of a true dragon" is so incredibly obscure and rare as to effectively be no ban at all. A Ban is also meant to be universal between the Demon Lord and his minions, though greatly reduced in strength for the Lord while potentially deadly for mooks.
I have natural sunlight or artificial UV rays (because my demons are shadow creatures), Vergil chose gold (because of the metaphysical significance between gold and love). For a lizardman/dragon, you'd want something similarly thematically appropriate of similar scale. Flame-retardant foam from a fire extinguisher burns them perhaps (dragons traditionally breathe fire), or they cannot break armor made from reptilian skin (so snakeskin leather is like full plate to them), or something weirder, like being unable to harm anyone prominently displaying the trappings of royalty (because dragons in the stories kidnap princesses all the time). Or you could pull on the strength/warrior-culture aspect of the lizardman/gnollmen cultures, and forbid them to ever attack someone who has not attacked them first, for a more psychological Ban. Or something else, but I hope you get the idea by now.