I was playing Skyrim and loving that I could shoot something with my bow(a bear, a draugr, etc.) and later loot it for a certain amount of arrows that I shot at it(of course, I never got back all my shot arrows). I then wondered, "What if you could do the same in Minecraft?" So that brought me to this mod request.
Bows could now be enchanted with looting, and depending on the level of the enchantment, a certain percentage of arrows shot at a mob would be dropped.
Level 1 : 25% of shot arrows
Level 2: 50% of shot arrows
Level 3: 75% of shot arrows
This would be most useful when killing bosses like the Ender Dragon, since it would take a ton of arrows to kill it even with the crystals destroyed. To balance it, it would not return all of your arrows(basically, requiring the player to craft more).