Blocking enchantment

There should be an enchantment so that if an arrow, fireball, snowball, or other projectile is heading towards you and you hit it with a sword enchanted with Blocking, you can hit it back at where it came from. Each level of Blocking gives you a 20% chance of completing the action, so Level V would be 100% chance of blocking. Blocking damages the sword every time it is used, and only works when the timing is correct. You can even block mob attacks. I think swords need a more defensive purpose not just for killing.