Silence, depicted by @mir.afaye
Silence, oftentimes called the Black Blade or the Black Blade of Ugaros, is the ancestral greatsword of House Ugaros. It is believed to be made of Yohm-kar due to sharing several of the attributes of yohm-kar (sharpness, never losing its edge, lightness, etc.), but due to its unique properties it is unclear if the blade truly is yohm-kar. While yohm-kar glows, Silence seems to shine with "anti-light," dimming rooms that it is in. The blade is also cold to the touch. When left in a bucket for a few minutes, the water in the bucket freezes.
Witch King Vizeroth IX found the blade during one of his many expeditions into the Silent Necropolis. Though he would eventually disappear in the ancient ruins, the sword remains as an heirloom of House Ugaros.