Sources: Dragon #331
Dragon Compendium Vol. 1
You have learned to fight with both ends of a pole arm.
Prerequisite: Two-Weapon Fighting.
Benefit: When wielding a pole arm two-handed you may choose to attack with the haft of the weapon. You may only perform this attack as part of a full-attack action. This additional attack is at your highest attack bonus and deals damage like a club of the same size as the pole arm. Although the haft does not possess any of the bonuses associated with the weapon (such as flaming), it does count as magic for the purposes of overcoming damage reduction if the weapon is enchanted. When using this feat, each attack you make in that round (the extra one and the normal ones) suffers a -2 penalty. You only receive half your Strength bonus on damage rolls with this attack. This feat cannot be used with a double weapon.
Normal: The haft of a non-double weapon is considered an improvised weapon and cannot be used as part of a full-attack action.