ShieldBreaker
Swaps to an axe when you attack a player with a raised shield, attacks, and then returns to your original hotbar slot.
ShieldBreaker is available on Minecraft 1.21.4 and later.
Swap Delay
Sets the delay in ticks between swapping to an axe and attacking.
Swap Back Delay
Sets the delay in ticks between attacking and returning to the original hotbar slot.
Double Click
Attacks again immediately after breaking the shield to knock the target back.
Limit to Items
Restricts ShieldBreaker so that it only functions while specified items are held. For more information, see the documentation for "Limit to Item" settings.