This is information that I've been able to gather from the in-game character screen data. Please note that this information is only gathered from the character screen, so if the actual application of formula such as Attack speed is different in practice than the character screen shows, this data will most likely also be faulty.
Color coded for (hopefully) easier readability. I tried to apply each color to the main stat that affects them. For example STR is red, Block rate is affected by STR, therefore Block rate is red. Stats unaffected by a main stat are Gold.
Haven't done thorough tests to try to determine a formula or amounts per level, however any items that say "+ Max HP/MP" are not affected by %HP/MP increases or decreases.
These are added to your base class %. For example a warrior with 123% base HP with Leadership would effectively have 135% base HP. A Magician with 97% base HP and Leadership would effectively have 109% base HP. Due to this Leadership is not synonymous with 1.2x more HP as some have claimed and actually has less of an impact on classes with higher HP such as Warrior, compared to ones with lower HP such as Magician. That said more HP is always good for a tank.
Traits like Apostle and Commando that have +5% P/M-Atk apply near the end of the P/M-Atk calculation, meaning they come into effect after increases to your weapon such as Staff Mastery or the Magician passive skill.
Approximately 1.25 per level starting with 10 at level 1.
+1 Block rate
+1 Evade rate
+0.8 Parry rate
+0.5 Atk speed
+1 Cast speed
WIS: (Note I was unable to accurately test Wis and Healing due to the huge range it has).
+0.8 Crit Rate
+1 M-Crit Rate
To further calculate the percentages the rates create you have to use what I call "Level modifider."
This is currently a number between 1.4 and 21 (at level 1 and 50 respectively) and is calculated by:
Level * 0.4 + 1
It will be referred to as "LvMod" below.
Accuracy rate / LvMod + 1 (1 is 1% base Accuracy)
Attack speed rate / LvMod
Crit Rate / LvMod + 3 (3 is 3% base Crit chance)
One of the only stats with a direct effect. 10% Crit damage = +10% Crit damage. It does not affect your current crit damage but rather adds 10% to it. Base Crit damage is 150% or 1.50x (exactly as the Char screen shows).
Cast Speed rate / LvMod
M-Crit Rate / LvMod + 3 (3 is 3% base M-Crit chance)
Same as Crit Damage except influenced by M-Crit Damage and activated by Spells.
Unsure. I have been unable to find an exact formula that works for all levels. It definitely gets worse with levels like everything else influenced by the LvMod, so I can only assume that it is involved at some point. Also as many other posts mention, capped at 50% reduction (but more defense is still marginally useful in cases where -def debuffs are used).
Evade Rate / LvMod + 5 (5 is 5% base Evade chance)
Parry Rate / LvMod
Block Rate / LvMod
Self explanatory. Every % of increased movement speed adds to this directly.
It is difficult to compare one stat to another (for example Accuracy vs Evasion) to determine how useful it actually is, especially when you can't measure the stats of mobs and bosses. I haven't done PVP testing so it's entirely possible there are changes in PVP.
An Upgraded weapon's stats (and presumably armor's) are applied to the staff's damage before other multipliers. For example a +4 staff's extra 14% Damage is first added to the base damage of that staff and then multiplied by a Magician's +10% Staff P/M-Atk which is added with their Staff Mastery %.
-Determine how much G-Healing, P-Healing and Wisdom affects Healing.
-Determine the range of damage/heal for Attacks and Heals.
-Determine exact formula for Defense damage reduction.
-Determine priority for damage reduction between integer reduction (Prevention/Declaration of Anger for example), % P-Dmg Reduced, and Defense damage reduction.
-Determine whether there is a cap for stats such as Attack/Cast speed, Crit/M-Crit rate, Evasion/Block/Parry, maybe even Crit/M-Crit Damage.
Hope it helps!
It seems that Trophies always add to your maximum stat and are unaffected by a class's natural stat %, similar to Titles. I tested this with Quade's Fang. It added 12 Str to a Thief with 116% Str. It added 12 Str to a Warrior with 125% Str.
Tested Wisdom with Gun RX79's Fuse. With +12% Wis from Certificates it still only increased Wis by 17.
Tested Agility with Robo VT080's Driver Chip and Maverick heroic trait. Increased Agility by 17.
Have not tested with % increase from Talents, but I would suspect it follows the same as the others.