If you're too chicken to fight a woman sitting on a bed with a knife (and get this--she is threatening herself, not the cops), then you don't deserve a policeman's pay. You're supposed to be a hero, not a big sissy. Let a civilian come in if you can't do your job. Any man can handle it except one trained in police work. I'd have no problem taking over if I found myself in the situation.
And in the past they would not have killed her over this. Duh. That "killing whenever you see something shiny" stuff is new, from the 70s. Before that obviously, they would have stood there like men and demanded the knife. If you're too chicken to grab her arm by yourself, then one cop goes behind, another in front, distract her, the one behind grabs it. The other 8 cops stand there talking about the weather while the two cops get the job done. That's how it would have been done before instruments of torture were legalized. Except that the useless 8 would never have been hired in the past and our taxes would be lower.
Maybe "only children" shouldn't be allowed to be cops. Anyone who grew up with siblings, especially brothers, knows how to fight.