If one had an encounter (let alone one that went bad), you better pray. I can tell you with some experience that a good dose of bear spray might be the only alternative. But for that the distance would have to be 30 feet or less, too close. It would be best to lay down a “fog wall” behind you as you egress to dissuade being followed. Forget the knife. If you close to a distance to use it on a human you are already screwed, how long a reach do these things have after all? Anyone recommending one has not been in an altercation with one, no disrespect to the suggestor. Situational awareness is the only thing that works, in the woods or on city streets. I would suggest reading the book “the gift of fear”, cannot remember the author. An excellent book.