The strongest hero.

You know, judging by the fact that Urgash is locked in Shio and Asra is "free," she (Asra) is stronger than Urgash.

So what? The nature of demons has always bestowed greater power upon their followers than other races receive from their own. Besides, Asra cannot leave her moon – she has weakened too much. I don't argue, Asra is stronger. But that doesn't mean that her followers are stronger than their demonic opponents.

Haha. You might as well say they got married. I think there's no need to speculate in this discussion: the fact is that the mage became a Dragon, with Asra's help, yes. But according to official sources, Asra enlightened Sar-Elam, and didn't engage in any kind of power transfer, at least I haven't seen anything about this aspect anywhere, which means, in fact, he acquired the power that surpasses Kha-Beleth himself, based solely on Asra's knowledge.

But the fact that she sympathized with Sar-Elam is a fact. No one was engaged in power transfers, yes. But if Kha-Beleth had based his power on Urgash's knowledge, the world of Asra would have been the opposite of others.
And, to be fair (this is, of course, silly), if Asra had opened her mind to Kha-Beleth, the Eighth Dragon would have appeared, and he would have been a demon.
Let's just forget about dragons. After all, Sar-Elam is a Dragon. That's how the world is: good is stronger.