Blocking enchantment

"Blocking" enchantment for shields. So, shields can now be enchanted on enchantment table! This would be one of them. Blocking increases the arc of blocking by 10 degrees each level, and an extra 10 degrees on level III, the last one. Normal shield is 100 degrees, Blocking I is 110, Blocking II is 120, Blocking III is 140. This would be a cool feature to add because, well, who doesn't want some nice enchants on their shield? I know that you can already use an anvil, but the shield doesn't have ANY unique enchantments–only unbreaking and mending. Some new enchantments for the shield would be nice.