I don't know a thing about Canadian law, but US law does allow justified self-defense.
Fleeing the scene is not a good idea. But, if you feel like you are not safe there, then leaving and going to immediately to the nearest place where you do feel safe is justifiable. You were just violently attacked to the point where you felt the need to use extreme measures, even deadly force, to defend yourself. If you feel your attacker might have friends waiting in the wings, you do not have to stick around to find out. Run away. Run to the nearest place where you feel safe and contact authorities from there. When asked why you left the scene, just explain that under the circumstances you did not feel safe there.
As humane as it may seem, rendering aid to your attacker is NOT a good idea tactically or legally. Your attacker may be "playing possum" trying to lure you into lowering your guard and approaching him. Even if you think you've disarmed your opponent, don't be so sure. He may have mulitple weapons concealed on him. Even if you think he's bleeding profusely, remember that we have an emotional reaction to blood. It always looks worse than it is. A little blood goes a long way. Your attacker may be insane, drunk, or on drugs. In his delusional state, he may wake up and mistake your attempts at CPR for a man-eating monster from Mars trying to suck his brains out. In his insanity, he may attack you again in a twisted case of self-defense. You are under no legal obligation to render aid. In court, the prosecution will not even bring it up. If it does come up, your attorney will have no problem explaining to the jury why you didn't try to help a man who just tried to kill you. In fact, if you do render aid, that may actually work against you. Your attorney will have a hard time explaining to the jury how you could have been so terrified of this man on moment that you had to use extreme, even deadly force against him, but then a moment later felt such compassion for him and felt so comfortable with him that you approached him and tried to help him.
First, assert that your actions were self-defense from the very first moment. When you make that 911 call, say "I was attacked by a man at (location), I fought back in self-defense. I think I hurt him pretty bad. I'm at (location). Please send an ambulance and some police officers." Your attorney can play that 911 tape for the jury and say, "See. Self-defense is not something we thought up after the fact to cover up a crime. My client felt he was acting in self-defense from the very first moment."
Second, don't try to make to much of a statement while you're still in an agitated state. Just say, "I'm sorry, but I'm still very scared, very paniced, and very upset by all of this. I'm not thinking clearly right now. I need to calm down and then I'm sure I'll be able to answer everything."
Third, you will probably be arrested. Don't be surprised. Guilt or innocence, what is and what is not self-defense... these are issues to be decided by a court. The officer in the field has a seriously injured, maybe even dead man and another man who says, "yes, I did that." If you were the seriously injured or dead one, you wouldn't want the officer saying, "Ah, looks like self-defense to me. Let's wrap it up quick and we can all be home in time for Hee Haw re-runs." No, the officer has to arrest you and let the courts sort it out. That's his job. Let him do it.
Fourth, as soon as anyone says, "You have the right to remain silent, you have the right to an attorney..." DO SO!
Finally, get the best possible attorney you can.
------------------
Chuck
Balisongs -- because it don't mean a thing if it ain't got that swing!
http://www.balisongcollector.com