I wish Canadian law was phrased the way it is in the US.

Here you're only permitted to use enough force to neutralize the person who is attacking you and any more is excessive. The 'fear of death or bodily harm' has no mention or relevance. I have a favorite example: An old man confuses me for the sailor that slept with his wife in 1954 (I know people who've been shot under similar circumstances) only he's feeble and I easily overpower him but in the process you break his arm (in this case he could have a gun or a knife or nothing...it really doesn't matter)...he could sue you here because you used an excessive amount of force over what was required to stop him.

Obviously perception is going to factor heavily when and if it goes to court but all a good lawyer needs to do is paint the right picture and the attacked becomes the attacker. Often times in situations like the example, both parties are charged but the defender gets the heavier sentence because the attacker is the one who got hurt while the original attacker only gets charged with attempted assault.