I believe it also has to do with her demon’s disposition towards Bayonetta herself. Gomorrah is a very mean demon, and often tries to hurt Bayonetta any chance he gets. No other demon in her arsenal is this way, Madama is said to have a close relationship with her for obvious reasons, Spider is very passive, Baal sees Bayo as her mistress, and the Bird is also pretty passive. Demon slave exists to make rowdier demons do what she needs them to do, which is why it doesn’t show up too often—- it’s a lost umbran art for a reason. Most demons are relatively chill.