AoE Radius Bonus
Increases the damage radius of area of effect (AoE) weapons like grenades or rockets. This is in addition to the base AoE contained on that specific weapon.
The angle of dispersion of damage from this weapon. A larger angle makes it easier to hit things, but this includes allies!
Critical Damage Bonus
The Critical Damage Bonus is added to a weapons Base Critical Damage for your Total Critical Hit Damage. This is a multiplier of your rolled Damage on a Critical Hit.
The amount of Damage that can be dealt. Weapons each contain a Damage range that is randomly rolled when an attack is successful. Items such as unique bullet types can increase the amount of Damage done by those weapons. Skills like Weaponsmithing will also allow you to increase damage of weapons you are currently using.
Bonus Range adds to the maximum effective distance of operation for that specific weapon type.
Shotgun Range Dmg. Reduction
A shotguns damage is reduced as the distance between the attacker and the target is increased. By increasing your Shotguns skill, this Shotgun Range Damage Reduction value can be...well...reduced.
Energy Weapon Damage Bonus
Bonus damage done to heavy armor when using an energy weapon.
Melee Critical Dmg. Bonus
The Melee Critical Damage Bonus is added to a weapons Base Critical Damage for your Total Critical Hit Damage. This is a multiplier of your rolled Damage on a Critical Hit.
Chance to Hit
How likely this character is to hit the broad side of a barn. Your Chance to Hit can be increased by improving your combat skills for that particular weapon. In addition, getting a height advantage or posting up around cover objects will temporarily increase your Chance to Hit.
The Maximum Range is the maximum effective distance of operation for that specific weapon type.
Jam Rate Reduction
The Jam Rate Reduction modifier will reduce the % chance of your firearm jamming. As you increase your combat skill level, you will can reduce the total Jam Rate of weapons relating to that skill. Each firearm has a % chance to jam when fired. If you want to spend less time dealing with malfunctions and more time popping your enemies, try to find weapons with a low jam rate.
Noise Radius Modifer
Things make noise. This thing makes that thing make more or less noise.
Each firearm has an Optimal Range of accuracy. Beyond that Optimal Range, you will see a steady drop-off in your Chance to Hit, up to the weapons Maximum Range.
Outside Optimal Chance to Hit
He's, like, a million miles away from you, so here's a penalty of, like, a million.
How easy is it to shoot the guy standing next to you? THIS EASY!
Point Blank Range
With some smaller firearms, when an enemy is within your Point Blank Range, you will get a bonus to your Chance to Hit. Longer weapons have a disadvantage of not being easy to maneuver when an enemy is in your face and you might get a reduction to your Chance to Hit.
Reload Cost Reduction
Reduces the AP cost when reloading a weapon in combat. Reloading your firearm in combat costs precious Action Points. As you improve your combat skills, you become faster at reloading in stressful situations. Reload Cost Reduction is subtracted from the weapons Reload Cost value.
Additional Shots Per Burst
Some weapons have multiple fire modes (Single Shot, Burst, Full Auto). Increasing your combat skill or modifying your weapon through Weaponsmithing can have the side effect of firing additional shots in Burst or Full Auto mode.