The Sweeping Edge enchantment is used with swords most of the time. This Enchantment will increase the sweep attack damage of the sword. This Enchantment increases damage up to 75% of the base damage of the sword and the highest level is level III (3).
A skeleton killed with Sweeping Edge (via screenshot)
Sweeping Edge is an enchantment that will allow you to deal with mobs quicker as it scales the damage done by your sword. The damage is scaled by 50%, 67%, and 75 at levels I, II, and III respectively.
Yes, you can get a higher level of Sweeping Edge with commands or other third-party editors. If you have other enchantments such as the fire aspect on your sword you will not do damage to mobs that were hit by sweeping edge unless it was a direct hit from the sword.
There are multiple ways to enchant a sword with Sweeping Edge. The most common and reliable way is through an enchantment table. Players must have the Lapis Lazuli as well as the experience required to get it.
An enchantment table offering enchantments for a sword (via screenshot)
Secondly, you can trade with Librarian Villagers that can be found in villages. Other ways that are less reliable but still can be used consist of fishing and loot chests. If you do manage to get your hands on an enchanted book with Sweeping Edge, you can use an anvil to apply it to the sword.
Applying Sweeping Edge III to a sword with an anvil (via screenshot)
Sweeping Edge is a handy and quite helpful enchantment for swords. Having increased damage is really handy when dealing with groups of mobs or mobs that have a lot of health such as Withers, Wardens, etc.
A. Sweeping Edge will increase the damage by 50% at level 1, 67% at level 2, and 75% at level 3.
A. No, as it would defeat the purpose of swords in the late game.
A. Smite is only effective on undead mobs where as Sweeping Edge does extra damage to all mobs.