Melee Weapons
Melee weapons aren't always what you need. Unless you are good at and enjoy playing knife-only games, the default M9 Knife can suit you well. This is because you rarely use a melee weapon in regular games, as having a non-ranged weapon gives you a severe disadvantage. You usually only use the knife to humiliate somebody who is not watching their back, often a camping sniper.
All melee weapons have infinite "ammo", have 100 accuracy, are not affected by "recoil" because they aren't guns, and have a special red x-shaped crosshair that doesn't get bigger. Melee weapons have another stat called "range", which is basically how long the weapon is and how close you need to be to your enemy for it to reach. Range is rated from 1 to 10, 10 being the longest.
All the melee weapons also have a secondary attack that can be used by pressing the right mouse button. It is always slower and stronger than the primary attack, but never to the point of decreasing the number of slashes to kill (always two). Therefore, the stats will only cover the primary attack, and the secondary attack will be only briefly described.
The portability is not at all accurate, or pertains to the realistic game measures at all. i.e. In the actual game itself, the portability of the M9 knife is 81, not 95, the heartbeat detector is 97 portability, not 98. These made up portabilities are just opinional gauges of their speeds, not to be taken professionally.
What was said here is backed up by the official Combat Arms wiki and the arsenal on CA main website.
 M9 Knife
|Damage||Slash: 27 /Stab: 80-90||Slash Rate||25||Portability||90||Range||3-4||Price||0|
Common Name: Knife
This is your default knife, which will suit you well enough unless you want an advantage in knife-only games. It is a good two-shot kill and has a high slash rate. You have to get pretty close to your enemy for the knife to reach. The secondary attack is a stabbing motion, which does more damage but not a one-hit kill. With this knife you will also find yourself moving pretty fast compared to other weapons, and you can also jump higher and farther, and is a good use for trying to outrun your enemy's.
Common Name: Sickle
This sharp farming tool is better than the M9 Knife in damage and slash rate. It is slightly heavier and also has a bit more range. Therefore, when playing a knife-only game, if somebody charges at you head-on with a regular knife, you should be able to get kill them with a headshot first because of the range. The sickle's secondary attack is a slow side-stab, which isn't really useful.
Common Name: Kukri
The Kukri is a long curved blade with a tremendous range. If somebody charges at you head-on with a knife or sickle, you should always win because you can get a headshot first. To compensate for this, the Kukri has a slower slashing rate. The secondary attack is a two-move swishing motion, which deals a lot of damage.
 G.I. Shovel
Common Name: Shovel
The G.I. Shovel has the exact same stats as the Kukri, and is basically the same thing. Long range, high damage, slow slashing rate (but without the rank restriction). On the downside, it makes you feel like a gardener.
 Bowie Knife
Common Name: Bowie
A sharp blade that is much like the Sickle, but slashes faster and has a slightly longer range. There is a high rank requirement on this melee weapon, so you may not reap its benefits immediately.
Common Name: Tomahawk
The Tomahawk has the longest range out of all the melee weapons, and it doesn't sacrifice much speed for it either. Otherwise, it is much like the Kukri or G.I. Shovel. The Tomahawk has a high price and also a very high rank requirement, so that not everyone can buy it and completely dominate a melee-only game.