Anvil of Thunder

(Complete Warrior, page 112, DnD 3.5)

[Style]

You have mastered the style of fighting with hammer and axe at the same time, and have learned to deal thunderous blows with this unique pairing of weapons.

Prerequisite

Improved Sunder, Power Attack, Two-Weapon Fighting, Weapon Focus (warhammer or light hammer), Weapon Focus (battleaxe, handaxe, or dwarven waraxe), STR 13

Benefit

If you hit the same creature with both your axe and your hammer in the same round, it must make a Fortitude saving throw (DC 10 + 1/2 your character level + your Str modifier) or be dazed for 1 round.