My first thought with this was that it was a magnifying glass + crystal, being used to see through Alma's eyes, because of all the rubbing. Though the guy did end up revealing he was looking through her eyes, with how much of his plan he's revealing now, my new guess is that this is actually his recording setup for when he does the audio broadcasts, and the whole thing's gonna be resolved when Fam sneaks this thing into the fight and Baron does the whole "accidentally broadcast your evil plans to the masses to break your hold on them" trope, while Seira argues against him.
Though, if that is what it is, having a fantasy manga where a villain has a recording setup with a regularass pop filter on it is pretty funny.