The Mortal Blade is a long, curved katana with a dark, almost black blade that seems to absorb light, featuring a blood-red edge that glows faintly when drawn. The hilt is wrapped in aged, dark brown leather, secured with ornate, tarnished silver fittings, and the guard (tsuba) is intricately designed with motifs of death and the underworld, reflecting its ability to sever immortality. The scabbard is lacquered in deep crimson with subtle crackling patterns, symbolizing its cursed nature.