The player is able to perform attacks while using an item such as a shield, spyglass, or crossbow. Doing so doesn't interrupt the item's use. Similarly, the player is able to initiate right-click actions during the attack animation, such as placing blocks or raising their shield. Items which have both a weapon attack and a right-click action can be used simultaneously, so the player can strip logs while swinging their axe, and throw a trident while thrusting with it. Attacking with a trident while also holding right-click to use it causes the player to attack using the back end, which isn't particularly relevant information but I thought it looked neat.

This allows the player to do things they can't do in vanilla, which they probably shouldn't be allowed to - for instance, attacking freely without ever having to lower their shield.