Reportedly: All overpowered random drop weapons were removed from the PC version and are only present in the unpatched Xbox360 version of the game. This item however is still present in the PC version.
This sword is crafted from a diagram found in Chapter I. The diagram for the sword can spawn randomly behind the secret wall in the burned down hospital (http://www.gamefaqs.com/boards/997903-the-witcher-2-assassins-of-kings/63484859) Also found in the chest after falling in the secret bath in The Rose of Remembrance mission.