I aggree that new arrows would be cool. Here are a few things I have come up with:
Shadow Arrows: Can be used to turn walls into shadows when needed, also can be used to drop through the ground (would be used to get to the boss). These also can shoot through walls and trees, useful for taking out unarmored enemies who are hiding.
Spirit Arrows: Can be used to turn enemies into spirits for a short time, thus making you invincible to them, and when you use Light Arrows (see below) on these spirits, it does massive damage (like 3 Master sword hits).
Light Arrows: can be used against any spirit or shadow enemy for massive damage, they will leave a beacon, usefull in dark rooms in shadow temples, or at night.
Fire Arrows: Basically like normal fire arrows, but on impact it is simmalar to Din's Fire in
OoT
Forest Arrows: Grows vines in a large circle if you need to climb to a ledge just out of reach or hookshot onto a ledge across a large gap.
Water Arrows: Douses any fire enemy, and can be used underwater.
Ice Arrows: Makes a solid surface on any body of water, blocks entrances, which can be melted by fire arrows. Also does good dammage on water enemies.
Electric Arrows: Travel very quickly. Does good damage to water enemies, and can be used like the dominion rod on any metal object.
Sniper Arrows: Come with a scope for your bow and are very slender, aerodynamic, and accurate. Basically used to pick off weak to moderate enemies from extremely long distances. can be paired with electric arrows to make them move faster.