You can upgrade the Quiver to hold 30 Arrows by either bying it at the Goron Shop for 2,000 Rupees or you can defeat the third level of Take 'Em All On. Following that, if you get 3,000-3,999 in the Pirate Hideout, you can upgrade it to hold 50 arrows.
Bow of LightEdit
You obtain this special bow after defeating Skeldritch in the Sand Temple. It is also neccesary in defeating Malladus in the final battle. This Bow, if you hold it for a few seconds before firing, can create Light Arrows. A Light Arrow's advantage is that it can hit multiple enemies at once, as it goes through enemies instead of just stopping once it hits one. Also, once you obtain the Bow of Light, you can never use the regular Bow again.