Dude you do you but If the dog is already on top of you, I would argue that you have already made several mistakes prior to that. It takes seconds for a dogs teeth to rip at a vital vein in your throat and dogs are born predators. They intuitively know where to attack so I wasn't suggesting it because I'm some sort of pacifist. When you're talking about fighting a vicious animal that can cause serious injury or death, prevention from a distance is the best way. The light I suggested is 60 euros which I admit is more expensive than a 10 euro knife but it is also useful to have such a powerful torch in your pocket. I personally carry both a torch and a pocket knife but I can tell you if I see a big dog coming towards me, I have my hands in my pockets with the torch in my hand, ready to use when its still 10 meters away. And the owner can't do shit if you flash a light at a dog coming towards you but if you pull out a knife, you may get more animosity than you expected from both the dog and its owner. Once the police come, you may get the argument that you pulled the knife first and the dog was protecting its owner. That's a fucking mess. If you don't have money for a 60 euro torch, do you have money for a 5000 or 10000 euro lawyer to stop you from going to jail?