Choose one type of melee weapon, such as longsword or greataxe. With that weapon, you do more damage on a critical hit.
Prerequisites: Str 23, Cleave, Great Cleave, Improved Critical (chosen weapon), Power Attack, Weapon Focus (chosen weapon).
Benefit: When using the weapon you have selected, you deal an extra 1d6 points of damage on a successful critical hit. If the weapon’s critical multiplier is ×3, add an extra 2d6 points of damage instead, and if the multiplier is ×4, add an extra 3d6 points of damage instead. (Creatures immune to critical hits can’t be affected by this feat.)
Special: You can gain this feat multiple times. Its effects do not stack. Each time you take the feat, it applies to a new type of weapon.
Source: Dungeon Master’s Guide (version 3.5), page 210. Slight wording changes were incorporated from a later version on page 72 of the Draconomicon that did not change how the feat worked.