So if a small 12 year old kid broke into my house and tried to take a swing at me and I killed them with a blow from a hammer - it would not be proportional.
If a 2m 150kg thug broke into my house and threatened to hit my 1.6m missus popped him on the nose with a hammer and he dies - it would be proportional.
When weapons are involved it becomes more serious. Someone with a baseball bat can potentially be more dangerous and the level of violence allowed to be used to neutralize the threat is much higher.
Well, it's potentially more complex than even that.
If you were a 12 year old housebreaker, would you go unarmed? Or even if you're just a physically small adult? This is why I'm against modern strict gun legislation, a regular person cannot defend themselves against any attacker if the attacker has a gun and the victim does not.
Guns are not the ultimate answer to the problem, addressing the causes of criminality is (and that's so so much harder). But should the general depravity that drives criminal behaviour not improve, and there is little sign of that, then calling the police is not going to work either. Vulnerable people without the means to employ their own security must be able to defend themselves in these circumstances, and so the law is a disgrace in this instance.
And of course, the police apply an entirely different standard to themselves; instead of arresting police officers for murder whenever they kill on duty as a matter of procedure, it's always assumed that the police officer did the right thing as a matter of course. Which is illustrative of how corrupt this modern policing system is: police officers are presumed innocent, and everyone else is presumed guilty. Unless they're powerful.
Local people should be paying a local officer who they trust to police their neighbourhood. People often reply "but that would lead to complete corruption", but at least the police would be corrupt in the way that the people who pay them wanted.