Man everyone's just full of information today, aren't they? I established what Lumanite is in chapte 2, but that was a long while ago and I figured a recap would be good. Plus this is an opportunity to establish that Auda herself actually knows what these things are. And now you know that they are specifically forged into a Moon Emblem. How they're forged is an answer for later.
Also Lubo did not wonder about Sabia's knowledge of Lumanite because her husband is Tyson, who has stated that he's seen Lobok use his power multiple times so it makes sense that Sabia would know about it as well. And Lubo bothered asking Auda in the first place because he himself did not know about Lumanite until literally 2 weeks ago. Lubo and Auda are the same age, so yeah.