The Two-Weapon Fighting feat reduces both penalties by 2. A combatant can use a double weapon to make an extra attack as if the combatant were fighting with two weapons. The penalties apply as if the off-hand weapon were light. If the attack roll result equals or exceeds the target's AC, the attack is successful, and the combatant deals damage. Roll the appropriate damage for a combatant's weapon.
Damage is deducted from the target's current hit points.
If penalties to damage bring the damage result below 1, a hit still deals 1 point of damage. When a combatant deals damage with a weapon in the combatant's off hand, a combatant add only one-half of the combatant's Strength bonus. When a combatant deals damage with a weapon that the combatant is wielding two-handed, the combatant adds one and one half times the combatant's Strength bonus. Light weapons don't get this higher Strength bonus when used two-handed. A Small combatant's unarmed strike deals 1d2 points of damage.