Better Leather gives Minecraft more options for crafting with leather. You can now bind regular leather with gold, iron or diamond to make it more durable. There are even more cows now for extra leather options as well.

With each newly enhanced piece of leather you can craft leather tools and swords. These will increase incrementally depending on if you use gold, iron or diamond.

Armor can be enhanced too but if you happen to find Ender Cows or Nether cows, you can create Ender and Nether armor as well!

This is a perfect mod to get more use out of leather and gives it more of a purpose in the game than just an intermediary item for making low impact armor.