Light Arrows are found in Stone Tower Temple after defeating the Garo Master.
Light Arrows can also be used to stun Ganon during the final battle. ReDeads and Gibdos will be paralyzed by Light Arrows, similar to the Sun's Song. If Link defeats a regular enemy with a Light Arrow, it drops a purple Rupee, and if used on a Skull Kid, found in the Lost Woods, it will drop a gold Rupee. They are the weapon needed to destroy the Six Evil Barriers Inside Ganon's Castle and defeat Ganondorf himself. Princess Zelda gives Link Light Arrows in the Temple of Time after he has awakened all of the Six Sages and obtained the Six Medallions.