"As long as it takes." To master the shield charm. To master wandless magic as a whole. Jade doesn't sound determined, just - factual. He'll master it, because he has to.

He looks at Professor Rammsteiner as another projectile bounces off the shield, creating ripples of light in front of him. "I can use the slingshot by myself. You don't have to stay."

Did he just dismiss a Professor from his own classroom? Yes, yes he did.