When wielding a second weapon a creature gains one extra attack per attack made as part of a focused attack, this includes the additional attacks made by spending additional AP. Unless otherwise specified attacks made with this second weapon are treated as Off-Hand attacks and the attacks made with the primary weapon are referred to as Main-Hand attacks.

Each Off-Hand attack made is treated as an additional attack as part of the Focused attack for the purpose of effects that modify a Focused Attack and the cumulative penalty to hit. If the attack made with the off-hand weapon is made with a light weapon the penalty for this attack is reduced by 1.

A creature may always choose to not make an attack with an off-hand weapon when making an attack even if they had used an off-hand attack on a different action. Each additional attack may separately designate an off-hand and main-hand weapon despite the previous attack; this means the first additional attack made could have a different weapon defined as its main-hand and off-hand than the focused attack.

A creature cannot use a limb utilized in a main-hand attack for an off-hand attack; such as using both hands for a two-handed weapon and then releasing the weapon to make an unarmed strike, but the creature could use a bite attack as a off-hand weapon as that was not a limb used to wield the two-handed weapon. This only applies to each set of attacks meaning a creature could use a two-handed weapon on one attack, then the next set of attacks perform two-weapon fighting using different weapons, and then return to using the two-handed weapon on the next set of attacks.

Examples
Example 1: The first attack made would be at no penalty but the accompanying off-hand attack would be made at a -5 penalty.
If a creature then chose to make an additional attack the main-hand attack would be made at a -10 and the accompanying off-hand would be made at a -15 penalty.

Going for a 3rd additional attack would then be made at a -20 penalty for the main-hand and a -25 for the off-hand.


Example 2: If the off-hand weapon is light the example would change as follows.

The first attack made would be at no penalty but the accompanying off-hand attack would be made at a -4 penalty.
If a creature then chose to make an additional attack the main-hand attack would be made at a -9 and the accompanying off-hand would be made at a -13 penalty.

Going for a 3rd additional attack would then be made at a -18 penalty for the main-hand and a -22 for the off-hand.

Double Weapons

Double weapons are a type of two-handed melee weapon that allows a creature to perform two-weapon fighting as if they were wielding two weapons by utilizing each end of the weapon. When using a double weapon to make a full attack action you treat each end as if they were a light weapon for the purposes of determining penalties from two-weapon fighting. Most double weapons are exotic and difficult to wield, but are also unique allowing a creature to add 1.5x their strength modifier on damage rolls with the main-hand and 1x on their off-hand attacks made with the weapon.