"Ahaha. I'm a ninja?" he says, with a grandiose bow, and continues with morbid cheer, "If I told you I'd have to kill you."

And then barrels on like he didn't just imply murder: "And oh, you mean this old thing? It does whatever I want it to - observe!" He spins the weapon in violent, expert circles, and strikes it into open space so panels and plating fly up and around, until it resolves into a massive fist-shaped hammer. "Pure high-grade titanium, of course."