Here is a list of Lara's weapons and inventory
Pistols
The pistols are your basic weapons. You should always use them when your target can not reach or hurt you.
Shotgun
The shotgun is a very powerful but slow weapon. It will take a second between shots for you to re-load, so you shold only use it when the enemy is far away and it will only take a couple of shots to kill it.
Automatic Pistols
The automatic pistols are like your pistols except they fire about twice as fast. They are a good all around weapon.
Uzis
The uzis are a powerful AND fast weapon which makes them one of the most valuable weapons in your inventory. They will take out a man in a couple of seconds.
M-16
The M-16 is one of the coolest weapons you use. It is your only long range weapon. If you see an enemy that is far away and you can not shoot it with other guns, use your M-16 and you will probably be able to hit it.
Harpoon Gun
The harpoon gun is the only weapon that you can use underwater. It will shoot three times and then you have to re-load. You can kill sharks, barracudas, and eels.
Grenade Launcher
The gredade launcher is the most powerful weapon you use. If an enemy is hit, it will be blown to smithereens leaving only what it was carrying. It has to be re-loaded after every shot, but it's effect is definetly worth it.
Flares
Flares are very useful in dark rooms or water. They can be thrown down dark hallways to illuminate the way or dropped into dark water to show the bottom. Because you only have a limited supply of these it is a good idea not to use them too freely.
Small Medipack
Small medipacks will bring your life to full from about halfway down. If you are not seriously injured, you can use them to temporarily boost your life until you need another.
Large Medipack
Large medipacks will return your health to full from about 1/5 of the bar full. Use them sparingly because there are less of them in the game than small ones. If you don't need full life, use a small medipack instead.