when the Age of Shadows came out, UBWS among other properties were put on all weapons. I believe at the time they did work, but only for a week or less if they did. It didn't take long to stop spawning bows with UBWS when it was stated that UBWS was for melee skills only. I have probubly like 20 of these UBWS bows sitting around collecting dust for the day they would get the 'promised' mod change of lower ammo cost. I have long given up on this concept but some of the UBWS bows are still pritty handy and so I am keeping them around.