Palutena's Arrow is Pit's neutral B move which is a projectile that is much like Link's Bow. Pit will pull his bow string back, and fire it when the the button is released. The main difference between Link's and Pit's arrow is that Pit's is much faster when traveling through the air, and Pit's can actually curve its trajectory if up or down is pressed right after it is released. Pit can also aim his arrows straight up or diagonally while he is charging them. Unfortunately, unlike Link, Pit can't hold the arrow indefinitely, as he will eventually release it. He can also shoot them straight up.
Pit's arrows can actually be curved around in a full circle if controlled properly and avoid going off screen.
Also, if two Palutena's Arrow's collide, they will cancel each other out.