I agree with feral's reply: I think you have never actually tried to use Aikido in a real hand-to-hand combat situation, let alone with the intent to prevent harm. I'll tell you what will happen: you will get your ass kicked spectacularly, because actually applying those techniques in the wild is incredibly hard and it gets much harder after the first punch that connected with your nose.

If you are going the way of fighting, the advise is simple: keep the fight as short as possible, by eliminating the opponents ability to fight on the first possible occasion. In one situation, a square hit in the face may remove all their resolve to continue fighting. In another situation, you may need to do serious damage. Whatever the situation: don't dance around and do what is required to prevent yourself from getting hurt.

(Luckily I've never been in an actual fight, but I regularly insist my jiu-jitsu training partners behave like they would in a real fight for a bit, instead of cooperating with the exercise. That always puts my ability to actually fight in a humbling perspective. What I learn from that is what you will hear others say: keep it simple (complex techniques fail much more often), hurt them as soon as possible (pain distracts people immensely) and keep it short (the longer the fight takes, the more chance for you to make a mistake, for him to grab a weapon, for someone to join in, etc.). A hard punch on the nose is the best start of any fight.)