Minecraft wiki entry for Sweeping_Edge, associated text: The formula for sweep attack damage is: 1 + Attack_Damage × (Sweeping_Edge_Level / (Sweeping_Edge_Level + 1)), rounded to the nearest integer. Here, the Attack_Damage is the sword's damage after applying Sharpness, Smite, and Bane of Arthropods. For example, an iron sword enchanted only with Sweeping Edge I deals 1 + 6 × (1 / (1 + 1)) = 4 damage to each mob hit with a sweep attack. A diamond sword enchanted with Sharpness V and Sweeping Edge III deals 1 + 10 × (3 / (3 + 1)) = 8.5 × 4.25 sweep damage. Any sword without Sweeping Edge deals 1 + Attack_Damage × (0 / (0 + 1)) = 1 sweep damage. Extra damage from Smite and Bane of Arthropods is applied against undead mobs and arthropod mobs, respectively.