They told me they're "interdimensional lamias, not exactly but you can call us that."

They have a (sacrificial) dagger too, not a trident like expected. The one who came to me said to show me something, then stabbed me in the heart with the dagger, then said to look at my dagger from the raising the sword ritual. It changed its color of energy, it's now filled up and looked "creamy", whereas before it was see-through.

Hmm...