Shield-Specific Knockback Enchantment.

I suggest adding a Knockback enchantment exclusively for Shields.

This enchantment would repel mobs and projectiles that hit the shielded player. The repulsion force should depend on the mob's size; for example, a zombie would be knocked back further than a ravager.

Regarding projectiles, only the ones that can normally be blocked by a shield (such as arrows or Blaze fireballs) would be deflected. A Ghast's fireball, however, would still explode on impact with the shield and could not be reflected.

This enchantment should be obtainable not only from enchanted books but also directly from the Enchanting Table. To balance this addition, I propose removing the Knockback enchantment from Swords, making the Shield the primary tool for controlling enemy positioning.

To make it even more fun, new advancements could be added, like "Stop hitting yourself!" — for killing a Skeleton with its own arrow deflected by a shield.