Calculating Weapon Skill Damage

Category: Guides
== Magic-Based Weapon Skills ==
*Damage = (( 1.5(Lv + 1)+2+ WSC ) * fTP + fINT ) * Resist * Elemental Staves * Weather * MDIF * Magic Damage Adjustment
*For ILvl weapons : Damage = (( 1.5(Lv + 1)+2+ floor(2.45*(iLvl-99)) + WSC ) * fTP + fINT ) * Resist * Elemental Staves * Weather * MDIF * Magic Damage Adjustment
;Where
:WSC: Secondary attribute like STR 30% (30% of your STR) (See individual Weapon Skill) 
:fTP: TP Multiplier (See individual Weapon Skill) 
:iLvl: the item level of the weapon 
:fINT : function of your INT and target's INT
:: for WS, fINT = 8 + ΔINT/2
:: ΔINT : difference between your INT and target’s INT (caps at 24 for WS), making fINT cap at 32.
:Resist : Possibilities are 
::No Resist(1/1)
::Half Resist(1/2)
::Quarter Resist(1/4)
::Resisted(1/8 and 1/16)
::Void(0)
:Weather
::if WS is used in single weather effect = 1.1 (+0.1)
::if WS is used in double weather effect = 1.25 (+0.25)
::Conversely, if WS is being used on the day where WS element is weak to, the multiplier is reduced by 0.1 and 0.25
:MDIF : ratio of your Magic ATK to target’s Magic DEF (Matk/Mdef)
:Magic Damage Adjustment : (1 + or - (Shells, Shining Ruby, sum of magic damage cut equipment))
::This parameter have denominator of 256 (1/256), for example
::Shell I is -24/256, Shell II is -36/256, Shell III is -48/256
::Shell IV is -56/256, Shining Ruby is -10/256, Bubble Curtain is -128/256
:: The smallest Magic Damage Adjustment number given by equipment capped the multiplier to 128/256 (0.5)
::Certain magic damage adjustments of particular monster family have been found:
::Ebony Puddings in Mount Zhayolm appear to take 25% bonus magic damage (+64/256).
::Eo'ghrahs in Grand Palace of Hu'Xzoi appear to take 87.5% magic damage (-32/256).
::Demon, Ahriman, Corse, Cardian have 25%(-64/256) magic damage cut
::Evil Weapon have 12.5%(-32/256) magic damage cut
::To some particular HNM, magic damage cut can occur occasionally when using the same element against that of HNM
::
== Physical-Based Weapon Skills ==
*Damage = WD * PDIF = ( D + fSTR + WSC) * fTP * PDIF
;Where
: WD: Base damage of your Weapon Skill
: D: Base damage of your weapon (e.g., Espadon = 43)
:fSTR: function of difference between your STR and target's VIT
:WSC: Secondary attribute like STR 30% (30% of your STR)
:fTP : TP Multiplier (See individual Weapon Skill) 
:PDIF: function of (your Physical ATK/target’s Physical DEF)
:WSC = integer(any secondary attributes) x @
 Level @
 Lv90... 0.85
 Lv75... 0.83
 Lv74... 0.83
 Lv73... 0.84
 Lv72... 0.84
 Lv67... 0.86 or 0.87 (perhaps 0.87)
 Lv60... 0.90 or 0.91 (perhaps 0.90)
 Lv40... 0.94 
 Lv37... 0.94 – 0.99
 Lv31... 0.94 - 0.99
*For example, suppose you are level 67 and have 100 STR and 100 MND and you use Swift Blade (STR 30%, MND 30%).
*WSC = integer[(100 x 0.3) + (100 x 0.3)] x @ = integer(60) x @ = 60 x .86
:(@ is 0.86 - 0.87 at LV67)
*WD = ( D + fSTR + WSC) * fTP
:For Sneak Attack with Thief main, the calculation is WD = ( D + fSTR + WSC) * fTP + DEX
:For Trick Attack with Thief main, the calculation is WD = ( D + fSTR + WSC) * fTP + AGI
:For Sneak Attack and Trick Attack with Thief main, the calculation is WD = ( D + fSTR + WSC) * fTP + DEX + AGI
* Only weapon skills that say "Chance of critical varies with TP" can have a critical hit within the WS without forced critical (i.e. Sneak Attack or Mighty Strikes).
** Base critical hit chance varies between weapon skills.
* WS gorgets from In the Name of Science add 0.097 to fTP for the first hit.
** They also increase WS accuracy, which applies to all hits.
* Hybrid weapon skills deal both physical and elemental damage and can be considered a 2+ hit weapon skill. The base damage of the elemental hit is based on the amount of physical damage done and TP.
== See also ==
* Weapon Skills
* Allakhazam : Discussion & Source
* FFXI Online : Detailed Discussion.
* VZX FFXI Doc
* Studio Gobli's Memo (Japanese). Also Studio Gobli's new website.
* Critical hit rate research -- (Broken, requires new link)