Flashing Weapon (D20 Modern Feat)
From D&D Wiki
You are able to wield a melee weapon with increased speed, but at decreased accuracy.
Prerequisite: BAB +3, Weapon Finesse.
Benefit: During your first attack of the round, you may make one extra melee attack that normally takes a half action. Every attack you make this round (including those during your first attack action) suffer a –2 penalty. This effect does not stack with the benefits of Double Blow (you may only benefit from one or the other in any single round).