The description is not 100% accurate.
You can still fire your weapon to get treasures and shoot objects (DO NOT SHOOT ANY PEOPLE OR MONSTERS EXCEPT WHEN PROMPTED TO IN THE MIRANDA FIGHT AT THE END AND WHILE FIGHTING IN THE MECH WITH HEISENBERG)
I did this on casual you can take a ton of hits and everything except bosses is 2 or 3 shot I also unlocked and used Chris knife from the extras.
I ran from all mechanical things in the factory as they are slow and not worth the Hassel.
As long as you don't physically damage an enemy with explosion or bullets you can get this. Yes flashbangs count. I avoided red barrels as well. So no idea if they void this trophy.
Even while fighting Heisanberg when you are knocked out of the mech DO NOT SHOOT WITH REGULAR WEAPONS. Swap to the knife again.
When fighting the daughter and you need to use a pipe bomb for the wall this is 100% OK she cannot be harmed until the wall is open so the explosion won't hurt her.
It is also OK to shoot the bells for the puzzle to go behind the painting.
When playing as Chris you must only use the knife on everything except to use the strike to take down the wall of mold.
NOTE Werewolves that die here from the strike do not count against you. It's a scripted event.
DO NOT USE THE STRIKE ON THE WEREWOLF FIGHT IN THE HOLE!! Only use the knife he will take way more knifes than any other boss combined but he will die eventually it seemed the only place I could hit him was his left knee. Every other spot was just swinging at air.
The fight with Miranda is straightforward if you have a few potions just block when she is floating cause I could not swipe her while she was in the air. When she comes down go to town on her.
When she digs her tenticles in the ground to grab you is when you are ok to shoot her. You will be prompted to press R2 at that point unload all holy hell on her.
Happy Hunting x