The percentage of bonus your character does in all forms of combat.
”— Fallout Tactics In-game description
Bonus Damage is a derived statistic in Fallout Tactics. It represents bonus damage done in all forms of combat. Bonus damage depends on race, traits and perks.
Super mutant characters have 6% bonus damage. Deathclaw characters have 3% bonus damage. Taking the Bonus Ranged Damage perk increases it by 15%, and Bonus HtH Damage increases it by 2 general points. The Finesse trait decreases it by 30%, The Kamikaze Trait raises it by 25%..