Offensive bonus (OB) is a bonus which is a rating of a character's ability to land attacks on an enemy and deal damage.
A character's naked offensive bonus is a function of their Level and Mood. Offensive bonus is increased through equipping a Weapon and practicing the appropriate Warrior skill for that weapon's class (Rogue skill for Short blades). When wielding a weapon, a character's Strength (Str) affects their offensive bonus.
Similar to parry bonus, a character's mood impacts not only their naked OB, but the OB gained from weapons.
The offensive bonus of a weapon itself can be increased slightly by having it Hardened at a Master Blacksmith for a fee.