The Knife is the default melee weapon give to a player when the game starts. The knife cannot be sold, is has no weight attribute and is the best way to reach the trader in large maps, as the speed of the player is multiplied by 25% and 55% as a level 6 Berserker.
The knife itself, is very weak but has a fast melee attack state, allowing you to temporarily stun a specimen by hitting it repeatly. This can save your life in the higher levels. However, Fleshpounds, Husks, Scrakes, Bloats and the Patriarch are not stunnable with the use of a knife, so don't think you are Chuck Norris and charge right into them with a knife.
- Using a knife: When the knife is equipped, the player can run sligthly faster, thus, the knife cannot aim or be throw, so use it as a getaway weapon. If you get cornered, try to knife your way out with the soft attack mode, stunning enemies for approximately 0.75 seconds. Using a knife can have advantages against the Patriarch, though. Just remember to bring pipebombs, place them and run past them as the Patriarch doesn't notice them in all his rage. When he is close to the Pipebombs, the player stuns the Patriach remaining him unable to move for one second. This is assuming you are using the Demolitions perk for pipebombs, as he can carry lots more than other perks.
- How not to use the knife: The knife is weak, so should not be used as a main weapon, unless the Berserker perk is chosen.