Opportunity = 1 + (0.04 * Opportunity Rank)
Offhand Reduction = 0.5 + (0.05 * Dual Wield Specialization Rank)
Lethality = 0.06 * Lethality Rank
Poison Bonus = 1 + (0.5 if Poisoned Target)

Average Weapon Damage = (Weapon Minimum Damage + Weapon Maximum Damage) / 2
Modifier = (Attack Power / 14) * 1.7
Base Damage = Average Weapon Damage + Modifier + Mutilate Bonus Damage

Mainhand Damage = Base Damage * Poison Bonus * Opportunity
Mainhand Critical Damage = Mainhand Damage * (2 + Lethality)

Offhand Damage = Base Damage * Poison Bonus * Offhand Reduction * Opportunity
Offhand Critical Damage = Offhand Damage * (2 + Lethality)

Minimum Mutilate Damage = Mainhand Damage + Offhand Damage
Maximum Mutilate Damage = Mainhand Critical Damage + Offhand Critical Damage