The term Moonweaver won't be revealed until much later in the story, but they're basically agents of the Old Gods who helped construct the secondary moons. There a lot of deeper lore to that, but right now that part is still fluid since it won't really come into play until much later in the story, so I probably won't develop that part too much until it becomes relevant XD.
There are also other things at play that I haven't finalized yet that could effect exactly how I portray the Moonweavers - such as the Court of Echoes, which is a secret society of host bodies who are possessed by "Echoes," soul shards of ancient god-adjacent beings.
The Echoes hop from body to body over the millennia and try to orchestrate the world's affairs from the shadows. Their exact purpose is still being refined in my head, but basically they seek their original bodies, which are sealed away in vaults in the Mythwater Expanse, and these vaults are equipped with enchantments that cause them to teleport back and forth across the Expanse and three Realms whenever a vault senses an Echo getting close to it. Thus, the Echoes cannot seek their vaults themselves and must act through various proxies.
The magic users who the story centers around are generally referred to as Battlemages. The first major story arc is the main characters competing in the World Battlemage Tournament, with the hopes of winning a Realmstone - this is a crystal realm anchor that prevents sea vessels and airships from being pulled into the Fae Realm or Demon Realm when traversing the Expanse. All seven main characters have their various reasons for wanting to explore the Expanse, and they team up to win a Realmstone so they can go on their individual quests, but also get pulled into a larger overarching quest as well.
And that's pretty badass to have carved moons! Reminds me of the moon in Majora's Mask XD.