That's fine, really, because before Tarn even finishes the sentence Wash is already moving. It happens quickly, all that tension coiled in him releasing at once, some twenty years of training and service, honed to a point. He's sure he can overpower him, just physically, but it's that he doesn't quite have the element of surprise, that's the problem.

Letting him keep the stunner isn't an option, though, and he turns his body against him, moving to try and drive the hard point of his elbow right into his side and make use of that to disarm him.