The word Sudarshana means “auspicious vision”. The Sudarshana cakra is the glance of the Supreme Personality of Godhead by which He creates the entire material world. Sa aiksata, sa asrjata. This is the Vedic version. The Sudarshana cakra, which is the origin of creation and is most dear to the Lord, has thousands of spokes. This Sudarshana cakra is the killer of the prowess of all other weapons, the killer of darkness, and the manifester of the prowess of devotional service; it is the means of establishing religious principles, and it is the killer of all irreligious activities. Without his mercy, the universe cannot be maintained, and therefore the Sudarshana cakra is employed by the Supreme personality of Godhead.
Source: A.C. Bhaktivedanta Swami Prabhupada (2014 edition), “Srimad Bhagavatam”, Ninth Canto, Chapter 5 – Text 5 & Introduction