A Link to the Past Upgrades
Listed below are all of the weapon and equipment upgrades that Link can acquire in A Link to the Past.
Arrows
Arrow Capacity
When Link first gets the Bow and Arrow he can hold a maximum of 30 Arrows. This can be upgraded all the way to 70 Arrows. Go to the Pond of Happiness which is located in the cave in the middle of Lake Hylia at the southeast portion of the Overworld. You will need Flippers in order to reach the island. Go inside and you will find a lake. It will ask if you would like to throw in Rupees. Throw in the biggest amount that it allows. It will say that you will have good luck or bad luck. Wait about 20 seconds and go to the pond again and throw in some more Rupees. Although on the Switch version of the game, you do not need to leave the pond area at all to continue throwing in Rupees. It will automatically restart the process about every 8 seconds. Once the total reaches 100 Rupees, a Fairy will come up and ask if you would like to upgrade Arrows or Bombs. It will upgrade your capacity, and you can keep upgrading until you reach a total of 70 Arrows.
Silver Arrows
After Link has acquired the Fifth and Sixth Crystal, he can buy a Super Bomb at the Bomb Shop, which is the Dark World counterpart of Link's house. Buy one and it will follow you around. Walk with the Super Bomb around the overworld to the Pyramid of Power found right in the center of the map. There is a crack in the wall on the left portion of the Pyramid and the bomb can be used to blow open a hole. Inside, you'll find a Fairy, and if you throw in the Bow and Arrow, the fairy will return it to you and will give you the Silver Arrows. These are much more powerful and will kill almost every basic enemy with a single shot. They are required in order to defeat Ganon using traditional means.
Bombs
When Link first acquires some Bombs, he can hold a maximum of 10 Bombs. This can be upgraded all the way to 50 Bombs. Go to the Pond of Happiness which is located in the cave in the middle of Lake Hylia at the southeast portion of the Overworld. You will need Flippers in order to reach the island. Go inside and you will find a lake. It will ask if you would like to throw in Rupees. Throw in the biggest amount that it allows. It will say that you will have good luck or bad luck. Wait about 20 seconds and go to the pond again and throw in some more Rupees. Once the total reaches 100 Rupees, a Fairy will come up and ask if you would like to upgrade Arrows or Bombs. It will upgrade your capacity, and you can keep upgrading until you reach a total of 50 Bombs.
Magic Meter
In the small area at the east side of Kakariko Village, where there is a single building, there is a cave with a hole next to it. Go up the stairs and use your Magic Hammer to pound the peg and then jump down into the hole. Walk up a screen and you'll find a green structure with a little bowl. Sprinkle some Magic Powder on it and a Bat will come out and cast a spell at you. This will make it so magical items will only consume half of the magic that they originally used. The bat makes it seem like he's hurting you, but he's actually helping you.
Boomerangs
Boomerang
While you walk through Hyrule Castle for the first time, you'll come across a treasure chest with the Boomerang. It can fetch items on the ground for you, as well as stun enemies.
Magical Boomerang
You can upgrade to the Magical Boomerang at the Waterfall of Wishing, located near the northeast portion of the Overworld. After acquiring the Flippers, simply walk into the waterfall, located just before the entrance to Zora's Waterfall. Inside you will find a pond where you can toss an item inside. Drop the Boomerang and the Fairy will appear and give you the upgraded Boomerang. This one is red and sparkly, but the big change is that it keeps flying until it hits the edge of the screen. This helps a lot in later dungeons where you can use this to hit a switch in the distance and retried items that are further away.
Swords
Fighter's Sword
Link's Uncle will give you this sword at the very beginning of the quest when Link ventures to Hyrule Castle. While it functions as Link's primary weapon for the early part of the quest, it is one of the weakest weapons that he has in his arsenal.
Master Sword
After acquiring all three Pendants of Virtue, Link can go to the northwestern corner of the Lost Woods where he can pull the Master Sword from its pedestal. This sword is twice as powerful as the Fighter's Sword and it will shoot beam blades when Link has full health. This item is required to break the barrier that leads to the Hyrule Castle Tower, where Agahnim awaits.
Tempered Sword
In the Dark World, go to the area just south of the Village of Outcasts, located where the Library was in the Light World. Use the Titan's Mitt to lift the rock and you'll find the Cursed Dwarven Swordsmith here. Talk with him and he will start to follow right behind you. Return to the Light World and head to the building that is one screen east of the main portion of Kakariko Village. Inside you can reunite the Dwarven Swordsmiths. Leave the house and go back in, and ask them to temper your sword, and they will do so for 10 Rupees. They will take it from you and will tell you to return shortly. Just leave the building, walk away for one screen, and then return to get the Tempered Sword. This red sword wields double the attack power as the Master Sword.
Golden Sword
After Link has acquired the Fifth and Sixth Crystal, he can buy a Super Bomb at the Bomb Shop, which is located in the Dark World, right where Link's house was. Buy one and it will follow you around. Walk with the Super Bomb around the overworld to the Pyramid of Power found right in the center of the map. There is a crack in the wall on the left portion of the Pyramid and the bomb can be used to blow open a whole. Inside, you'll find a Fairy, and if you throw in the Tempered Sword, the fairy will return it to you and will give you the upgraded Golden Sword. This is the strongest sword in the game dealing twice the damage of the Tempered Sword and four times the damage as the Master Sword.
Shields
Fighter's Shield
Link's Uncle will give you this shield at the very beginning of the quest when Link ventures to Hyrule Castle. It is the weakest shield in the game and is not able to block many attacks at all.
Red Shield
Link can get the Red Shield two different ways. It is sold in a shop in the Dark World for 500 Rupees, but the free way to get it is by getting it right after you get the Zora Flippers. Once you get the Zora Flippers and leave Zora's Waterfall. There is a small waterfall located at the top-left of the area just outside of Zora's Waterfall. Swim into the waterfall and it will take you to a fountain. It will ask you to throw something in. Throw in your Fighter's Shield and in return the fairy will give you the Red Shield. This upgrade allows Link to block weak fire attacks.
Mirror Shield
The Mirror Shield is the dungeon item found in Turtle Rock. It is much stronger than any other shield in the game, and it can block strong beam attacks. While it is the dungeon item of Turtle Rock, it is a completely optional item.
Mails
Green Jerkin
The Green Jerkin is the one that Link has at the very start of the game. It is Link's classic green tunic and it will be the tunic worn through the majority of Link's quest.
Blue Mail
The Blue Mail is the dungeon item found in the fifth dungeon of the Dark World, the Ice Palace. This will reduce the damage that Link takes from attacks by 1/2. This tunic is completely optional during Link's quest.
Red Mail
The Red Mail is the final dungeon item that Link will acquire, found deep within Ganon's Tower. Link will take 1/2 the amount of damage he took with the Blue Mail, or 1/4 the amount of damage he took while wearing the Green Mail. This tunic is completely optional during Link's quest.
Gloves
Power Glove
The Power Glove is the dungeon item of the Desert Palace. It gives Link the ability to lift up the white rocks, allowing Link to traverse new areas of the Overworld, as well as uncover new secrets.
Titan's Mitt
Found as the dungeon item in Thieves' Town, the Titan's Mitt lets you lift up the black, heavy rocks found throughout the game. This item is required to navigate portions of the world, including being able to reach each of the final three crystals in the Dark World.