Enchanted bow

The enchanted bow is a bow endowed with magic to make it so that any arrow fired from it will never miss its target. It was originally collected by Walsh, a powerful wizard of Oz, before he was overthrown by the Wicked Witch Zelena. It was then stolen from her by Robin Hood, and taken by a vengeful Rumplestiltskin; he proceeded to give it to Snow White so that she could assassinate the Evil Queen, but she fails due to the intervention of Prince Charming.

Before the Curse
Walsh, also known as Oz, the Great and Terrible, sated his time in the magical land of Oz by collecting a wide range of enchanted trinkets; one such trinket was apparently the enchanted bow. When Walsh is overthrown by Zelena, the Wicked Witch of the West, the bow falls under her possession - that is, until Robin Hood is sent by Rumplestiltskin to steal the Elixir of the Wounded Heart. During a confrontation with Zelena, Robin sees the bow and a sign beside which explains that any arrow fired from it will never miss its target. He picks it up and prepares to fire, at which Zelena makes duplicates of herself so that he won't know who to aim for. He makes the wrong choice, hitting a vent instead, but manages to leave with both the elixir and the bow... but Rumplestiltskin doesn't get what he wants. A while later, Robin uses another of Zelena's trinkets he managed to snag to change his face before heading into Rumple's Dark Castle to rob a magic wand. He uses the bow to ward off the Dark One, proving its prowess when the arrow changes direction in mid-air. However, Rumple is simply able to pluck the arrow from his chest with no damage done, proceeding to take Robin prisoner. He tortures him for a while until his maid Belle sets him free out of pity, and Rumple plans to use the bow on Robin once he catches up to him. As it turns out, Robin has a pregnant wife, and Rumple finds himself unable to leave a child fatherless. As such, when he fires an arrow from the enchanted bow, it doesn't hit Robin, meaning that Rumple must have intended it to miss. This allows Belle to see the good in her captor, who proceeds to store the bow away amidst his other magical items. Snow White goes to Rumplestiltskin for help assassinating Regina, and he gives her the enchanted bow. She prepares to fire an arrow at the Evil Queen as she rides past, but Prince Charming jumps in the path of it, taking it in the shoulder to stop his true love's heart from turning dark.