Gloom Blade

As black as coal, this short sword grows more potent the farther it is kept from light. It acts as a +1 short sword when in dim light. In darkness, it acts as +2 short sword. When surrounded by supernatural darkness, such as in an area of deeper darkness, it acts a +2 short sword and bestows the benefit of the Blind-Fight feat on its wielder. In daylight or bright illumination, the sword temporarily loses all its magical enhancement bonuses and acts as a masterwork weapon, though it resumes its magical functions once it is no longer in the bright light.