Looks like someone kidnapped you. Then offered you a duel. Before that he/she told you about his or her life to help you deciding about his/her worth! Then only you can compare the between you and the attacker!
This doesn't make sense. If someone want to hurt you, it's your every right to try your best to protect yourself. If it needs to kill someone to save your family or yourself, there is no problem I think.
Will a noble person come to kill you? Nope.
But here in this scenario, I am not killing the one who is threatening to kill me. I have to choose the person to kill as a way of saving myself. Pick someone innocent, or be killed myself.