Cane of Byrna
In The Legend of Zelda: A Link to The Past, the Cane of Byrna is found in a cave on Death Mountain, south of Ganon's Tower in the Dark World. Link must already possess the Magic Cape, Magic Hammer and the Titan's Mitt to obtain this item (or he can walk across the spikes, but in doing so he will take a lot of damage and at least 2 fairies are recommended for this). When used, the Cane of Byrna creates a forcefield around Link, making him invincible (so that he takes no damage from attacks or spikes), and consuming magic power. The Cane of Byrna has essentially the same affect as the Magic Cape, but the difference is that the forcefield will damage enemies if they make contact with Link and the enemies can see you during its use. Throughout the game, there is no necessity for this item, and the game may be completed without it.
It also appears in Soul Calibur II as one of Link's weapons.