yeah, deathwand crossbow from the arms and equipment guide. both wands are considered "wielded" along with the crossbow. you can fire off any one of the three as per normal action / attack rules. they just all three count as "wielded". would be an odd accompaniment to a dual wielding wand type. ^^
i have this sudden vision of someone wielding two of these crossbows, one in each hand, for the wands. might be fun to make them repeating, auto-reloading crossbows.