In The Legend of Zelda, Link finds the Magical Sword in the possession of a man who lives underneath a grave in the Cemetery. The Old Man requires that Link to have at least twelve Heart Containers in his life meter before he gives Link the Sword. The sword has the same properties as all of the other swords in the game, such as the ability to shoot Sword Beams, but is simply stronger. In fact, the weapon is entirely optional, as only the Silver Arrows and any kind of Sword are required to defeat Ganon.
The Adventure of Link
In The Adventure of Link, Link departs on his quest with the Magical Sword in his left hand and the Magical Shield in his right. Link is able to augment the Sword's ability to fire Sword Beams with the Fire spell, which allows the Sword to shoot fireballs even if Link is not at full health. The Sword will also do more damage if Link levels up his Attack stats. The Sword is pictured on the game's box art.
Link wields a Sword very similar to the Magical Sword in The Legend of Zelda animated series. It is much smaller than any depiction of the Sword featured in official art, however, and resembles a long dagger more than a Sword. Link is almost never shown to slash with it, using it only to parry and attacking using its Sword Beams. In the episode "Stinging a Stinger", the Sword is given the name "Crissword."
Captain N: The Game Master
Although not explicitly referred to as the Magical Sword, Link in Captain N: The Game Master wields a sword similar to the Magical Sword. Like in the Zelda animated series, Link can use it to zap enemies, and this time, he can be seen attacking enemies with the Sword rather than just using it to defend himself or parry.
The Magical Sword is one of Link's weapons available in Soulcalibur II, although it is known as the Magic Sword instead. Paired off with the Magical Shield, the Magic Sword and the shield can be bought in the Aldebaran Shop, Algol Shop, Pollux Shop, or the Merak Shop for 3000 Gold while playing the Weapon Master Mode. Although Link's offense and defense will not increase when he equips these weapons, the Magic Sword will cause 40% block damage, compared to the usual 10%.
Causes 40% block damage
Weak against physical impact
Ancient arms hidden deep in an underground tomb. This powerful sword holds an enchantment that counters the forces of darkness, and its holy aura allows it to deliver damage to the enemy even without making physical contact. The shield is enchanted with a spell that protects its user from enemy magic, but the actual shield itself is quite old and is weak against physical impact.
In Hyrule Warriors, the Magical Sword, along with the Magical Shield, appears as a weapon for Link. It is part of the Hylian Sword weapon type and is the third weapon tier of it. The Magical Sword can be obtained as a reward through Adventure Mode. An 8-bit version of the Magical Sword from The Legend of Zelda, added in the Majora's Mask pack DLC, is also used for Impa's Naginata weapon type.
There is a some debate as to whether or not the Magic Sword is in truth the Master Sword. Zelda.com's encyclopedia section refers to them both as the same weapon, but this website's canonical status is dubious. Some fans speculate that since the Master Sword's absence in a game featuring Ganon is curious, the two Swords could be the same (although it should be noted that the Master Sword did not appear in Four Swords Adventures either). This is doubtful, however, as the Magical Sword is never referred to as the Blade of Evil's Bane, only as a very powerful Sword that is not even essential to defeat Ganon. It is noteworthy however that all official art and Soulcalibur II depict the Magical Sword differently to the Master Sword, as either a blue Sword with red edges (The Legend of Zelda and Soulcalibur II), or a silver blade with red gems embedded in its hilt (The Adventure of Link).
In subversion to all of this however, retroactive artwork of the Magic Sword illustrated by Katsuya Terada in the Official "A Link to the Past" and "Link's Awakening" guides, depict it as being the Master Sword. While this would settle the matter of the sword's identity, in an ironic twist, said artwork depicts Link as wielding the same shield across all four contemporary games at the time, rather than the familiar cross-emblazoned shields in the artwork for the first two Zelda titles seen before.
Artwork from The Legend of Zelda
Artwork from the Japanese strategy guide of The Legend of Zelda
Artwork of the Magical Sword featuring golden tints