General Weapon and Item Stats Guide

The Base Stats

Strength
-Grants 1 point of armor per point
-Increases damage for barbarians by 1% per point ex: 1337 strength would result in 1337% extra damage; if said barbarian normally hit 100, they would then hit 1437.

Dexterity
-Grants some dodge per point, starting at .1%; grants less at higher levels of dexterity.
-Increases damage for monks and demon hunters by 1% per point.

Intelligence
-Grants .1 point of resistance per point.
-Increases damage for Wizards and Witch Doctors by 1% per point.

Vitality
-Grants 10 points of health per point; increased if character has % health affixes.
-For ever level past 35, vitality grants an extra point of health. ex: at level 36, it will give 11 hp/point, and at lvl 37 it will give 12 hp/point.

Items
 

DPS
Determined by taking the average of the maximum hit and the minimum hit ((min+max)/2) and multiplying it by the attacks per second.

Damage
Damage on weapons is randomly selected for maximum and minimum values from a pool.

For example, look at this axe:

The axe's minimum damage will range from 2 to 3, and the maximum will range from 3 to 4. At this time I am 99% positive that the minimum damage will NEVER equal the maximum damage, ex: the axe will not roll a 3 for minimum, and a 3 for maximum. If the minimum rolled a 3, them max would have to be 4 (the only remaining number from the range 3-4 including all whole numbers).

Attack Speed
Attack speed in Diablo 3 is displayed in attacks per second. This is constant value for all item types other than select legendaries. It is affected by attack speed affixes. If you desire to know the attack speed in the amount of seconds it take per hit, take the inverse of the attacks per second (1 divide by the attacks per second).

Affixes
Note: like damage and armor, all affixes are randomly selected from a pool for each item (except legendaries) the values for each affix are then also randomly selected from a range of possible values (INCLUDING legendaries).

Additional Damage
Minimum damage: Added to the base minimum rolled by the weapon.
Maximum damage: Added to the base maximum rolled by the weapon.
Damage %: Multiplied by the maximum and minimum damage on the weapon.

For example if you find a weapon that say +31% Damage, such as this:

The 840.2 DPS damage indicated is the damage output after the calculated +31%.

Elemental damage:
Each of the possible elemental damage affixes, if they happen to be rolled onto a weapon, are also rolled from a range of minimum and maximum damage.

Note: The elemental damage is already added to the maximum and minimum damage vales of the weapon when found.

The various types of elemental damage all provide special bonuses when the weapon they are applied to scores a critical hit. Note: this does not affect spells for the witch doctor and wizard, as their damage is already of a specific damage type. An example of a possible exception is spectral blade, which normally deals physical damage.

Arcane: critical hits cause a silence effect, preventing spell casts.
Fire: critical hits cause a fire damage over time effect to be applied to the target.
Cold: critical hits cause the target to be frozen for a short time.
Lightning: critical hits cause the target to be stunned for 2 seconds (?).
Holy: Unknown (extra damage to undead regardless of critical?).
Poison: Unknown (I believe it simply applies a damage over time effect).

Attack Speed
Increases the speed at which attacks are delivered.

Attack speed %:  Simply increases the attack speed of the weapon and any skills, resulting speed is the product of original attacks per second * (1 + AttackSpeed%)

On Hit Affects
Life: per offensive damaging attack, gain # in health
Life steal: gain % of damage you deal as health. (put this here to keep it near life on hit)
Life on kill: gain # health per enemy death "
Knockback: % chance to knock target away on attack
Fear: % chance to cause enemy to run away in fear on attack
Stun: % chance to stun enemy on attack
Blind: % chance to blind enemy on attack
Freeze: % chance to freeze enemy on attack
Chill: % chance to chill enemy on attack (note: chills slow attack speed also, slows do not(?))
Slow: % chance to slow enemy on attack
Immobilize: % chance to immobilize on attack

Critical Attacks
Critical attacks are attacks that do 150% of normal weapon damage, or 50% extra. The base critical hit chance is 5%.

Critical hit chance: increases your critical chance by the displayed %.

Critical hit damage: increase your critical hit damage by the %; NOTE: This damage is added to your critical hit damage; ex: if you found an amulet that gave 50% critical hit damage, it wouldn't cause your critical hits to do 175% damage; they would now deal double damage, 200%.
 

Defensive Stats
 

Armor
Armor reduces damage taken from all sources, including elemental. Armor is also selected randomly from a range.

Resistances
+ to all resistances adds an equal amount to each of these:

Physical resistance: Reduces physical damage taken.
Arcane resistance: Reduces arcane damage taken (shares a spot with holy resistance on the stat page).
Fire resistance: Reduces fire damage taken.
Cold resistance: Reduces cold damage taken.
Holy resistance: Reduces holy damage taken (shares a spot with arcane resistance on the stat page).
Poison resistance: Reduces poison damage taken.

Dodge
Dodge is a chance to completely avoid damage, increased by dexterity (there is no +dodge affix).

Misc. Stats
Gold find increases the amount of gold found by a set %; if you find gold piles averaging 100 gold, if you gain 25% gold find, they will instead average 125 gold.

Magic find increases the amount of magical items found by a set %; this includes magical (blue) items, rare (yellow) items, and legendary (gold) items.

Gold drop and health orb radius increases the distance from which you can pick up health globes or gold coins.

Class Affixes
There are multiple affixes for skills for each class.

-Reduced skill costs (fury, hatred, arcane power, spirit, mana).
-Increased critical hit chance (3-5%).
-Increased damage.
 

More Info:

+% crit chance and +%crit damage are universal stats which affect all attacks, so any increase to those statistics raises the crit chance and damage multiplier of all attacks, including spells.

For instance, on the Demon Hunter, if you have the Archery passive and wield a 2H Crossbow, you get +50% crit damage, and your bombs and traps blow up for huge crits, even though the crossbow doesn't have anything to do with them, really. Same goes for Wizards and their spells.

All casting is influenced by +Attack Speed%. Try it yourself, equip a fast 1H weapon and then a slow 2H weapon and try casting some signature spells and other spells like Arcane Orb. The time between shots of both is much longer with the big slow 2H weapon (but they hit harder).

This is somewhat of a design problem, as I see it, because with a fast weapon you can shoot out a bunch of orbs real fast and blow through all your arcane power, but each one won't hit as hard as ones from a slow weapon (a slow weapon of equivalent DPS has a much higher damage range per hit). But your arcane power doesn't regenerate any faster when you wield a fast weapon, so your use of arcane power is less efficient with a fast weapon.

I'm not sure how weapon speed affects channeled spells like disintegrate. Are the ticks further apart but hit harder with a slow weapon? Is arcane power used up faster with a fast weapon? I haven't tested this yet.

As for on-hit effects I know there's a lot of funniness with that, there are lots of threads specifically about +life on hit and spells, and which ones get it and which don't, if and how often or how many times you get it for AOE spells, what % of the effect you get per mob or for different spells or per tick of DOTs or spells with AOE durations, etc.

One last thing, I've gotten tons of help from the Diablo 3 Gold Secrets By Peng Joon guide, it is a premium guide, so there is a small fee for it, but well worth it.