Knockback

Knockback is an uncommon melee enchantment in Minecraft 1.21. Knockback shoves whatever you hit away from you, adding extra horizontal launch on top of the small push a normal sprint-hit already produces.

Its opening level already delivers a noticeable boost — +3 blocks of knockback — and it climbs from there to a maximum of level 2 (II) on your sword.

Knockback tops out at level 2, shown as II on the sword, and the gap between the levels is where the enchantment's character really lives.

With only two levels, each one adds roughly three blocks of additional knockback, so Knockback II can fling a mob about six blocks back. The effect is purely positional — it adds no damage — but it buys you breathing room between hits.

Knockback fits exactly one item — the sword — and nothing else will accept it, so it is a dedicated sword enchantment through and through.

Knockback has no exclusivity conflicts at all, so you can layer it onto a sword alongside every other enchantment that sword accepts without having to give anything up.

Knockback can be rolled directly at an enchanting table, where reaching its top level of II on a sword generally wants a fully bookshelf-powered table at roughly level 6. When the enchanting table refuses to offer Knockback, the same enchantment is available as a book from loot chest and villager trading for anvil application.

Its selection weight of 5 makes Knockback an uncommon roll: it appears with middling frequency when enchanting a sword — common enough to plan around, but not guaranteed on any given roll.