少减ab的是双巧手，不是双武器。

大概是硬加了游侠专长但没有游侠等级所以没起效，算是人物设计上的bug吧

看了下wiki，帮你破案了，和楼上猜的一样，“Also Dual-Wield feat is tied to the ranger class not the feat itself, which is there just for information purposes apparently - it fakes adding Two Weapon Fighting and Ambidexterity only if the armor they are wearing is less than 4.”，游侠的双武器是职业等级赋予的，专长没有实际作用