A minute detail I noticed is that the sword that each twin yields is different. In a way, Lumine's is in shape of a moon and Aether's in shape of a star? :
Game Genshin Impact Traveller Lumine Cosplay Prop PVC Sword Sky Blade Replica Weapon Props Halloween Christmas Party Accessories - AliExpress
Fichier STL Traveler's Original Swords -- Aether and Lumine -- Genshin Impact -- Splited Print Ready ⚔️・Plan pour impression 3D à télécharger・Cults
i ramble in the tags — i designed a lumine sword for fun 😭 it changes...