Adherence to sound martial doctrine requires that you do all you can to make the fight forced on you as unfair as possible. Outgun your assailant if you can, and outflank him and attack him ruthlessly from behind if you are able.
A fight is not a sporting event; there are no rules making it fair. There are rules on when application of force is justifiable, but when it is, the defender is just in doing whatever it takes to defend himself, using overwhelming force and good strategy.
The one who causes the violence to take place is responsible for his own death if he is killed in self defense.