Beatrix is the youngest of the 'Sibyl Sisters' who all have a deep connection to The Unda. She runs her own mod shop, “Beat Frequency”, which supplies Muses with their weapons. Since Cyrus can vibe with any mod, he can use any weapon Beatrix has available. The most basic version of each weapon type is available at the beginning of the game, but new, stronger models can be purchased or upgraded as the game progresses.

For clarity, the weapons on display in her shop are all props, since her mods only manifest real weapons in The Unda.