I've always thought that Gray's Anatomy should be required reading for anyone who chooses to used edged weapons in self-defense.
If you study the anatomy, you can see how the nerves, blood vessels, and anchor points for the muscles and tendons are arranged.
I also have considerable experience in treating knife injuries as I was a paramedic for many years.....so, if you couple this with certain martial arts, I believe it would help your outcome in a knife fight.....and, perhaps, influence your choice of weapons.
I have tried to identify vital targets on different angles and surfaces of the human body, with the idea that I have a traget regardless of which part of the assailant's body is closest to me.
I have also sparred with magic markers as knives, so that I can see which part of the body that I've cut on my sparring partner (comparing with anatomy charts afterwords).
I've also smeared fake blood on my ka-bar, and practiced flicking it in a mannequin's eyes to momentarily sabotage the assailant's sight so that I have a reaction gap to exploit.
And so on.