Charged Thunderstorm (3.5e Equipment)
From D&D Wiki
Requiring a caster level of 30, the Charged Thunderstorm weapon enhancement is no easy feat to place; it is however, well worth the effort. Charged Thunderstorm adds 1d4 +1/2 strength modifier in damage to the enchanted weapon. Additionally, after landing four successful blows, the weapon can unleash a furious gale that sweeps forth with terrible force, blasting away small foes and scouring away the flesh of those large enough to withstand its torrent. The storm lasts until the end of your next turn, encompasses a burst 3 +1 for every 10 strength. It deals twice your strength modifier in damage to enemies within the burst.
Market Price: +3 bonus