The Needler- This weapon is really odd. It is harmful, but it dosen't hurt the enemy right away. I personally think that the needler is useless, but it is Captain Keyes choice while on a mission with Master Chief.
The Pistol is my favorite of them all. It has a 2X scope and it fires 12.7mm semi armor-piercing rounds. If you are good at "head shots" then this is the weapon for you to use.
The Sniper is my second favorite. It has a scope of 2X and 10X. Its a gas-operated magazine fed weapon. It fires 14.5mm armor piercing fin-stabilized rounds. The sniper also has not vision. The sniper comes great in handy when shooting from far away distances.
The Shotgun carries 8 shells and fires 3.5" rounds, so don't come close to it when you come in contact with an enemy, it will kill you instantly if at point blank range. The shotgun is mostly used in multiplayer for defending the base.
The Assualt Rifle comes usefull during the flood. It fires 7.26 armor piercings and holds up to 60 bullets.
The Plasma Rifle is a great weapon to use. It stuns your enemies and you can kill them. It keeps on firing until it over heats and you have to wait about 2-3 seconds. I personally would use this weapon for kills.
This thing is pretty much useless. I think that this weapon was made so Bungie could have just one more weapon in it. I hope that this weapon does not make it in Halo 2. I think that it would be a waste for Halo 2. So, don't use this weapon, basically, unless you want to die.
The Frag Gernade and the Plasma Gernade are the only two gernades in Halo:CE. The frag gernade bounces around, so it would be best if used near alot of enemies. The Plasma is mostly used for sticking on to vehicles.