There are six categories of weapons that do five types of damage. What category of weapon you will be best with is based on your skill level. The categories are: unarmed (which can be modified with gloves), melee, throwing, small guns, big guns, and energy weapons. The types of damage these weapons can inflict are: normal, laser, flame, plasma, and explode.
Normal damage covers bullets, shells, cutting instruments, blunt force, and HTH attacks.
You are still able to use weapons you are not skilled in, but because you are not as competent in firing and maintaining those types of weapons, your accuracy will suffer. Your skill level will not modify damage done by a weapon. The muscle operated weapons, unarmed, melee, and thrown will change their distance or damage based on your strength stat, while firearms may get a damage or piercing modifier based on the ammo used. Skill level will only modify accuracy. All weapon weights are assuming an unloaded weapon, and the AP cost for reloading any weapon is 2.
All unarmed damage is assuming a Strength of 10.
The rock can also be used as a throwing weapon.
All melee damage is assuming a Strength of 10. All AP costs are for melee actions only, not throwing with the same weapon. Melee weapons are arranged according to damage but check AP as well. For example: The sledgehammer does more damage than the combat knife, but the combat knife requires 1 less AP making it the better weapon.
The spear and throwing knife can also be used as throwing weapons.
All thrown weapons are assuming a Strength of 10. All AP costs are for throwing actions only, not melee with the same weapon. When you throw a weapon if you have a duplicate in your inventory, that item will be added to your active item slot at no penalty.
The rock can also be used as an unarmed weapon; the throwing knife and spear can be used as melee weapons. The pulse grenade only affects robots
The type of ammo used may modify gun damage. The damage for burst weapons may look unimpressive but keep in mind they will fire multiple rounds. Most of the burst weapons have pathetic single fire modes; you may want to keep a short-range burst weapon in one hand and a long-range single shot weapon in the other. Guns are organized by type (pistols, SMG's, shotguns rifles).
The BB gun is an Easter Egg from "Christmas Story" it may get an increased chance to shoot out an eye, and the hunting and sniper rifle may get increased chances to hit (unconfirmed)
Big guns do obscene amounts of damage to lightly armored creatures, but I would not suggest specializing in them unless you have very high strength. The guns are heavy and require a high strength stat to wield, and you need to be strong enough to carry around the very heavy and very expensive ammo required of them.
If the minigun looks really weak at first glance, keep in mind it fires 40 times per burst. I strongly advise against using the rocket launcher at close range, the result will not be pretty.
These are generally the most powerful weapons in the game. Energy weapon damage is not modified by the type of ammo used like other weapons. Remember laser and plasma weapons do different types of damage.
Again, keep in mind the gatling laser is a burst weapon and the amount of damage it does is misleading. In general plasma weapons do more damage at the cost of less range, the choice is up to you, but the turbo plasma rifle will probably be your best weapon. I have not determined if the alien blaster does laser or plasma damage, if you have info on this please e-mail me.