Base damage is the sum of these following things:

• Weapon Base Damage (D)
  
• Ammo Damage (if the calculation is for ranged attack) (aD)
  
• STR - VIT Difference Function (fSTR or fSTR2)
  
• Weapon Skill Secondary Attribute Modifier (WSC) (only for WS Calculation)
  

So, Base Damage = D + (aD) + fSTR(2) for normal attack
and Base Damage = floor((D + (aD) + fSTR(2) + WSC)* fTP) for WS

for THF Main, SATA + Normal hit is calculated as Base Damage = floor(D + fSTR) + Total AGI + Total DEX.
Similarly, THF Main SATA+WS is calculated as Base Damage = floor((D + fSTR + WSC)* fTP) + Total AGI + Total DEX

See also Edit

• Level Correction Function and pDIF
• Calculating Physical Damage
• Calculating Magic Damage
• Calculating Weapon Skill Damage