'About to lose her life' is a gray scale.
As I said, the test is an objective one, not subjective. In other words, the trier of fact must itself into the position of the person being attacked, and judge whether or not
a reasonable person in the position of the person being attacked would have felt that the attack was life threatening. Which brings us to your next comment . . .
What amazes me are the people who think that they can sit behind a desk in their office attire and judge whether a person who has been abused by the same man for years is truly in danger or not. If that isnt arrogance of legendary proportions I dont know what would be.
Yes, it probably is arrogance - but it's the only thing we (the legal system) have. What's the alternative - to have the person being attacked be allowed to set the standard as to whether they were justified in using deadly force? Think about it. The attacker is dead and the person who was being attacked is on trial for killing them. What do you think the defendant in that case (the person who had been attacked, killed the attacker and is now on trial for murder) is going to say on that point? "Yes, the dirty look that he gave me made it very clear that my life was in danger, so I shot him."
See the problem? So the legal system must "arrogantly" make a judgment as to whether or not the actions of the person being attacked in killing the attacker, were really justified. The only way to do that is by an objective determination that takes into account all of the circumstances that took place at the time.