The job of a sensei. which means in Japanese person born before another but mostly used as teacher. An official sensei is 3rd dan and above a sensei is not a black belt. A black belt is a beginner in the martial arts and has started his journey of becoming a great practitioner in the martial arts of what style they train in. A sensei job is to guide and teach the student in combative skills and harness there inner warrior spirit. He can show you the tools and how to use them then its up to you to put it all in place. As a 4th dan in martial arts i try my best to train my students well to protect them selves. But all i can do is guide my students to walk a better path and incourage them to do better for one self.