Darth Vader was always arrogant. He forgot that Obi-Wan had spent 20 years in the desert, with nothing to do but learn new ways to mess with him. Or the story of how Darth Vader touches Obi-Wan Kenobi's lightsaber after the events on Cloud City but forgets about that little Force-trick of psychometry. Obi-Wan has one last surprise for his old Padawan.