Here is every item and piece of equipment Link can find in Twilight Princess HD, where to get it, and what it does. Most of the main items are the prizes for beating each dungeon's mini-boss; the rest come from shops, side quests and the people of Hyrule.
In HD you can put items on three buttons (X, Y and R), swap them instantly on the GamePad without pausing, and aim the bow and Gale Boomerang with the GamePad's gyro.
What Changed From the GameCube and Wii Versions
NewGhost Lantern: from Jovani at 20 Poe Souls; lights up when an Imp Poe is nearby.
ChangedWallets hold more: 500, 1,000 and 2,000 Rupees.
NewColossal Wallet: 9,999 Rupees, for clearing the Cave of Shadows with the Wolf Link amiibo.
Changed When your wallet is full you can still open Rupee chests; the extra Rupees are lost instead of going back into the chest.
Swords
Wooden Sword: Rusl, Ordon Village. Link's first sword, used for practice early on.
Ordon Sword: the sword Rusl made for the royal family. As Wolf Link, during the twilight, sneak into Rusl's house to take it.
Master Sword: drawn from the pedestal in the ruins of the Temple of Time in the Sacred Grove. It breaks the curse that turns Link into a wolf, so from then on you can change forms at will.
Light-filled Master Sword: in the Palace of Twilight, the Sols fill the Master Sword with light, letting it cut through the palace's darkness.
Shields
Ordon Shield: in the storage loft of Jaggle and Pergie's house in Ordon Village. It's wooden, so it burns if it touches fire.
Wooden Shield: sold at Malo Mart in Kakariko Village for 50 Rupees. Also wooden.
Hylian Shield: sold at Malo Mart in Kakariko Village for 200 Rupees, and later by a Goron merchant in Castle Town. It's made of metal and never burns.
Clothing
Hero's Clothes: given to you by the Light Spirit Faron after you clear the twilight from Faron Woods.
Zora Armor: given to you in King Zora's tomb in the Kakariko Graveyard. It lets you breathe underwater indefinitely.
Magic Armor: sold at Malo Mart's Castle Town branch for 598 Rupees (you'll need a bigger wallet to afford it). It turns damage into a loss of Rupees instead of hearts, but it drains Rupees while you wear it, and it makes Link heavy if you run out.
Dungeon Items
Gale Boomerang (Forest Temple, from Ook): creates a whirlwind that can lock onto up to five targets, stunning enemies, cutting ropes and spinning windmills. It can carry Bomblings and other objects too.
Hero's Bow (Goron Mines, from Dangoro): comes with a quiver of 30 arrows. Combine it with bombs to fire Bomb Arrows.
Clawshot (Lakebed Temple, from the Deku Toad): fires a chain that grabs targets, vines and enemies and pulls you to them.
Spinner (Arbiter's Grounds, from the Death Sword): a spinning top Link rides along rails and grooves in the walls, and uses to turn gears.
Ball and Chain (Snowpeak Ruins, from Darkhammer): a heavy wrecking ball that smashes ice, armor and walls.
Dominion Rod (Temple of Time, from the Darknut): brings statues to life so you can control them. Its power fades after you leave the temple, and has to be restored later in the game before you can use it on the Owl Statues.
Double Clawshots (City in the Sky, from the Aeralfos): a second Clawshot that lets you swing from target to target without touching the ground.
Other Equipment
Iron Boots: Mayor Bo in Ordon Village gives them to you after you beat him at sumo. They let you walk underwater, stick to magnetic surfaces, and stand your ground against things that would push you.
Lantern: Coro in Faron Woods gives it to you. It lights torches and dark places, and burns spider webs. It runs on Lantern Oil, which Coro also sells.
Slingshot: sold at Sera's Sundries in Ordon Village for 30 Rupees.
Fishing Rod: Uli in Ordon Village gives it to you after you return her cradle.
Hawkeye: sold at Malo Mart in Kakariko Village for 100 Rupees after you win Talo's archery game. It lets you zoom in, and works with the bow to aim at faraway targets.
Horse Call: Ilia gives it to you in Kakariko Village after you return Ilia's Charm to her. Use it to call Epona wherever you are.
Ooccoo: hidden in a pot in each dungeon. Ooccoo can take you out of a dungeon, and her son Ooccoo Jr. brings you back to the spot where you left. Neither works in boss rooms.
Empty Bottles: there are four. See the Bottle Locations page.
Capacity Upgrades
Wallet (from Agitha; see the Golden Bugs page)
Wallet
How to get it
Holds (HD)
Original
Starting wallet
Start of the game
500 Rupees
300 Rupees
Big Wallet
Give Agitha your first Golden Bug
1,000 Rupees
600 Rupees
Giant Wallet
Give Agitha all 24 Golden Bugs
2,000 Rupees
1,000 Rupees
Colossal Wallet
Clear the Cave of Shadows with the Giant Wallet (needs the Wolf Link amiibo)
9,999 Rupees
n/a
Quiver
Quiver (30 arrows): comes with the Hero's Bow.
Big Quiver (60 arrows): win the STAR minigame in Castle Town the first time (10 Rupees to play).
Giant Quiver (100 arrows): win the harder second STAR course (15 Rupees to play) once you have the Double Clawshots.
Bomb Bags
Bomb Bag #1: Barnes sells it at his bomb shop in Kakariko Village for 120 Rupees.
Bomb Bag #2: Iza gives it to you after you help her clear the rocks from Zora's River.
Bomb Bag #3: free a Goron trapped underwater in Zora's Domain (you'll need the Zora Armor and Iron Boots).
Giant Bomb Bag: score enough points in Iza's Rapid Ride on Zora's River. It doubles the capacity of every bomb bag.
Each bag holds one type of bomb: 30 regular Bombs, 15 Water Bombs or 10 Bomblings. With the Giant Bomb Bag, that becomes 60, 30 or 20.