The Knife is the default melee weapon available in all CrossFire versions, except CF Vietnam, where a Wood Hammer replaces it. This weapon is always available in all bags that every player have and cannot be removed or thrown away during matches.
The knife is the lightest weapon in-game, and many players pull out this weapon to traverse large spaces, move quickly, or jump higher. The knife has a slicing (or slashing) primary attack, and when executed, the player slashes once across and follows up with a thrust. The secondary attack is a downward angled stab, done by the player flipping the knife in his or her palm, then stabbing.
Being a default weapon, Knife has only moderate power, requiring 3-4 hit (primary) or 2 hit (secondary) to kill armored opponent - it can perform 1-hit kill with secondary attack but players must aim for the head or a specific area on opponent's back to deliver maximum damage. However, this weapon is still very dangerous thanks to its fast attack and light weight (Only outclassed by Dual Karambit).
CrossFire's default Knife model was actually taken from John Rambo's survival knife from Rambo First Blood Part 2 movie.
There is a word says "RAMBO(R) FIRST BLOOD PART II" in the Knife's blade.
The knife is the only Melee weapon in CF to feature 3 different attack types. Aside from the two main attacks, it's possible to tap LMB to execute fast slash, which is much more effective than holding LMB.
This does includes Laser Dagger, which shares animation with the Knife.
3-4 slashes are enough to finish someone off. Two stabs to the chest will kill, and when combined, it's best to quickslash an enemy just once or twice after successfully stabbing them. Note: Many believe that 'the knife is for pros only all other is for the weak and noobyish.
The secondary attack can sometimes one-shot on the body, but at other times only leaves the enemy with 10 hp left,leaving you to finish them off with one normal slash. There is also an area on the back, around the shoulder level in the middle that you can one-stab kill.
All the Tournament variant of the Knife received buffed stats, allowing it to 1-hit kill with RMB anywhere on the body minus leg/arm hit. Only CF Japan has this buff on the default knife, and CF Vietnam has this buff on the Knife Hunting.
After the King Mode updated in CF VN, there's a glitch that if you join the room whatever time after the battle to choose the King/Queen, you will hold the Knife as default for unknown reason, until another battle.
As of October 2010 patch, the Knife has been permanently removed in CF Vietnam, where a Wood Hammer has replaced it. This has been done by the publisher VTC Online in an effort to save CF from being forced to close down following a violence controversy scandal. It is said that a 16 year old teenager played CF learnt how to using the knife to kill opponents, did the same thing and killed his grandfather so he could steal money to spend at the Internet store. During a later statement, he claimed that he learned everything from CF, stating that "I thought he would later respawn". The media took this to put a lot of pressure on CF, and VTC Online subsequently had to promise to "limit violence in CF as much as possible". They then released the October patch entitled "Call Of Duty", which changed a lot of the violence aspects in the game (removal of blood, kill/death terms changed to scoring/KO, headshot icon changed into an apple, disappearing dead bodies...), thus gained permission to continue operating CrossFire in VN. Tons of players got mad because of the changes made, but the gaming community understood that this was inevitable.
Comeback of the Knife
In the recent years, Knife Stripe becomes the temporary replacement for CF Vietnam players, often available as event prizes or daily mission prizes or on the Webmall. Also, the WCG and CFS variant was added since 2012, allowing players to spend money to buy it for a long time due to its cheap price. As of 28th November 2013, a permanent variant, Knife Black, is finally added, giving players the chance to own the Knife permanently. Because this weapon is in Black Market, VTC avoided troubles with the government since not everyone can own it. Following suit, Laser Dagger and Knife Ultimate Gold were added without any trouble. In March 2015, an event called "Nhận quà vĩnh viễn" allows players to obtain a free PERMANENT Knife Black. It simply involes logging in on March 30th, then play for 120 minutes (2 hours). Because the requirement is so simple, this is considered a major comeback of the Knife in Crossfire Vietnam. Also, if the players buy Shovel-Born Beast and switching to another melee, there's a chance that players will get this Knife as well.
After the July 2012 patch, many players are unable to play CF Vietnam due to the 31_3 client error that happens almost immediately upon entering any room or when the match starts. This error is supposed to detect weapon skin hack (i.e changing Barrett to Barrett Royal...), and it has been upgraded to work against Wood Knife hack (as its name suggests, this hack turns the Wood Hammer into a Knife but with Wood texture). However, this update has one major flaw: It detects player's default melee weapon as Wood Hammer (to prevent Wood Knife hack), but whenever a match starts, there is a brief moment that player character is shown holding the Knife (the higher their ping is, the longer it is visible) before switching to the primary weapon. As a result, 31_3 is triggered, rendering players unable to play any match since they can't avoid the "holding knife animation sequence". Eventually this glitch was fixed, but many players already lost the chance to do Daily mission for the Treasure Hunt event.
The return of the Knife
Throughout the years, it's been widely thought that the original Knife is permanently gone in CF Vietnam - however it's not true, since the Wooden Hammer was a new weapon that replaced the Knife, so it still exists in CF Vietnam client. After King Mode's update, it's been proven that this weapon is still obtainable when joining mid-game (See screenshot below), albeit not freely outside King Mode. Finally when the Field Shovel-Born Beast was added, players can now obtain the default Knife any time they want by brute-forcing through the weapon's Lucky Draw function. Although it's still hard to actually get it, the Knife has officially return to CF Vietnam in the form of an obtainable weapon for all Shovel-BB players.