It can cut through any object and cause instent death with a single scratch.
When unlishing it's untimate power it's weilder gets covered in a physical manifestation of the sword's dark energy. It is up to the user to be able to turn that dark energy into light energy. If the dark energy is not conquered, it can cause madness.
When an enemy is attacked and cut in any way by the sword, they will be engulfed by the darkness and killed. The pain will be intense.