Minecraft wiki entry for Development_versions, associated text: Players can now only attack when the weapon is fully charged.
Different weapons and items have different attack ranges, all separate from the block breaking reach.
3.5 blocks for all swords.
4 blocks for tridents and hoes.
3 for all other items.
The attack timer can be charged to 200%.
The attack timer reaches 200% after the recharging animation of the sword is fully complete.
A 200% charge is required for critical hits and the sweeping attack.
A 200% charge will also deal higher knockback while sprinting.
Weapons with shorter cooldowns give victims shorter attack invulnerability times (invincibility frames).
The attack control can now be held down, attacking whenever the attack cooldown reaches 100%.
It is now possible to hit mobs through non-full-sized blocks such as grass.