Figuring out Defense, Armor and Resistance scaling should be very easy if the mechanics are similar to WoW.
The formula from WoW is:
%DR = 100% - (100% / (x*Armor + 100%)), where x is a different number for each character level.
On the other hand, it appears that Precision is directly proportional to Crit, as in:
%Crit = y*Precision, where y is a different number for each character level
Since both of these formulae are directly proportional (ie, linear no threshold), you technically only need one datapoint to figure out the scaling value - simply divide one value by the other. However, to account for rounding error you will want to average out at least 3 datapoints.
If %DR is the displayed damage reduction (from Defense, Armor, or Resistance), then let %ieHP equal incremental effective HP (ie, the percent gain in effective HP over zero damage reduction):
%ieHP = (100% * %DR) / (100% - %DR)
This can be shown to be directly proportional to Armor as below:
However, if there is a threshold for Defense (ie, below a certain amount of Defense you get zero damage reduction) the formula will no longer be direct proportional. This appears likely as I've seen several screenshots of players with positive amounts of Defense but 0% damage reduction.
Another thing we are unsure of is if there are any hard caps or diminishing returns thresholds. I suspect that kind of info will only become available once people are at level cap though >_>.
Attack - Increases damage dealt. Applies to all damage types (physical, elemental) and sources (it affects your pets). 1 Attack == 1% damage.
Precision - Increases critical strike rate. Unknown formula. Appears to be diminish in effectiveness as your character levels. May vary per class. At level 13, my Wiz has 87 Precision with a 6.16% chance to crit. This translates to each point of precision being worth 0.071~% crit; roughly 14 precision = 1% crit at level 13.
Defense - Reduces damage taken. Applies to all damage types (physical, elemental) and sources (melee, ranged, dots, etc). Appears to be diminish in effectiveness as your character levels. At level 13, my Wiz has 89 defense, with a 59.38% reduction to all damage. This translates to each point of defense being worth 0.668~% damage reduction; roughly 15 defense = 10% damage reduction at level 13.
Vitality: This translates directly into Health. Amount of HP per point seems to vary slightly per class.
Secondary Attributes
All percentage based bonuses (excluding +Crit Damage %, because that goes over 100%) appear to be multiplicative, not additive. EG: 2x 50% dodge buffs would result in a 75% chance to dodge, not 100%. [(1 - 0.5) * (1 - 0.5)] = 0.25
Armor - Reduces physical damage taken only. Appears to be diminish in effectiveness as your character levels. At level 13, my Wiz has 145 armor, with 18.24% physical damage reduction. This translates to each point of armor being worth 0.126~% phys DR; roughly 80 armor = 10% phys DR at level 13.
Resistances - Reduce damage to the respective element by a percentage. I have found no resist gear yet, so I cannot give any values.
Critical Damage - Crits of all type deal 150% damage baseline. The + % Crit Damage affix increases that percentage.
Block - Block reduces the damage of a physical melee/ranged attack by a flat value. Blocks are not a complete negation of that hit, as they were in D2.
Dodge - Dodge completely avoids the attack. It appears to only work on melee/non-spell ranged attacks. There is no dodge animation, it is just a combat roll.
Weapons 2 Handers
Highest base damage, so you will hit the hardest
They appear to have lower weapon spread than faster weapons, ensuring you do big damage more consistently
Animation times are slower
Less resource generation (for monk/barb/DH in some cases)
Less crits/procs
Dual Wield
Innate 15% attack speed bonus
Weapon have large damage ranges, so if the RNG gods are unkind you may be T_T
Lots of attacks = lots of crits and procs
More resource generation
Remember that with dual wield, the attacks alternate between main and offhand
1H + Shield
Armor boost, obviously
You can block attacks
The damage lost here is actually relatively small (in theory). Essentially, you do a bit less DPS than dual wielding (assuming the dual wielding weapons are identical in DPS/stats)
Another thing we are unsure of is if there are any hard caps or diminishing returns thresholds. I suspect that kind of info will only become available once people are at level cap though >_>.
The tooltips for each resistance clearly state that each resistance value reduces the damage from that element by a percentage.
Core Attributes
Secondary Attributes
All percentage based bonuses (excluding +Crit Damage %, because that goes over 100%) appear to be multiplicative, not additive. EG: 2x 50% dodge buffs would result in a 75% chance to dodge, not 100%. [(1 - 0.5) * (1 - 0.5)] = 0.25
Weapons
2 Handers
Dual Wield
1H + Shield
Weapon Speeds
Anyone else find anything useful?