First of all, it depends on the cause of the incident, whether it is an emergency or not, and whether it is possible to escape. If a fight or quarrel is caused by your double agreement, no matter who starts it first, it belongs to a fight with each other. In this case, if you kill someone, you should be sentenced for intentional injury or intentional homicide.
Secondly, if it is an emergency, it depends on the specific situation of the other party besieging you and whether the other party is still attacking you when you fight back. If the other side has stopped attacking you before you launch a counterattack, resulting in a fight between the two sides, then you are intentionally hurting. If you defend yourself when they attack you, and the other party kills you by mistake, it may be justifiable defense, but it may also be excessive defense, depending on the specific situation. According to your description, it is beyond the limits of self-defense.
Third, it is more important to look at your subjective purpose. If your purpose is to get back at them, it must not constitute self-defense.
Finally, the legality of weapons is also very important. If you happen to have these things on the ground around you, or your daily necessities, such as kitchen knives and axes for chopping wood, these are all legal. If you usually carry a controlled knife with you, it is definitely illegal and does not constitute self-defense, because you have the subjective preparation to hurt others in advance.