Bring back Sword blocking

I think this addition would be very suitable, especially for those who don't have a Shield or whose Shield is broken; when holding two hands, they will still prioritize raising the Shield. The Sword will still reduce damage by 50% in the blocking direction and only reduce the player's speed by 50% to balance it compared to the Shield, while also reducing the knockback force when knocked, potentially providing a block delay twice as fast as the Shield (around 130ms). I think the sword-blocking animation should be implemented in third-person view before 14w30a because it looks better with more accurate blocking direction.