Uh - [ look, it's not every day you get to explain being what gets you hunted over five countries. Especially over a network where she doesn't want to plant that idea. ] To be Grisha is to be born with the ability to manipulate matter in different ways. In Ravka, when Grisha are discovered, we're taken for training before we join the Second Army. So it would be the Second Army that's the organization, while to be Grisha is just to be... different.