Double Sword (3.5e Equipment)

This weapon may be used two-handed (forsaking the secondary attack) or as a double weapon. On each melee attack a creature proficient with this weapon makes, he can choose two squares he threatens that are adjacent to each other, and his attacks apply to creatures in those two squares equally (though never to the same creature twice if it fills more than one square). The wielder can use this ability on any attack, even an attack of opportunity or a cleave attempt.