The user has access to an object that grants them supernatural powers, these can be magical objects of great or destructive power, or technological weaponry. If the user already possesses supernatural abilities, the objects are mostly meant for letting them access and/or enhance their powers, or grant them new abilities.
Albus Dumbledore (Harry Potter); via the Elder Wand
Harry Potter (Harry Potter); via the Elder Wand
Lyra Belaqua (His Dark Materials); via Alethiometer
Will Parry (His Dark Materials); via Subtle Knife
Shadowhunters (The Shadowhunter Chronicles); via steles and holy weapons
When Caryn Clay (Fly Girl series) has a Thunderbird feather on her, she has limited control over the weather and can fly.
Kratos (God of War); via various weapons and accessories (most notably the Blades of Chaos/Athena/Exile). It should be noted that Kratos is also granted innate, magical powers over the course of his storyline by various gods and other entities.
The Hōgyoku (Bleach) can manifest a person's greatest desires and potential, granting them unimaginable & unique powers and abilities.
Ichigo Kurosaki (Bleach) uses a manifested Shinigami blade of his powers...
... while the mask supplements his Shinigami powers with Hollows, giving him a vast increase of strength, speed, durability and spiritual power, including augmented Getsuga Tenshō.
The Visoreds (Bleach) using their Hollow Masks to augment their superhuman powers and abilities, increasing their strength, speed, and durability, and are even able to use the Hollow/Menos Grande/Gillian/Adjuchas/Vasto Lorde power to fire a Cero.
Grimmjow Jaegerjaquez (Bleach) using the Caja Negación cube to create a pocket dimension field to imprison Ulquiorra Cifer.
When Kaname Tōsen (Bleach) puts on his Hollow Mask, his strength and speed increase and develops high-speed regeneration.
Yukio Hans Vorarlberna (Bleach) using his Fullbring ability via his game console to create a pocket dimension.
Stand Arrows (JoJo's Bizarre Adventure)
Holy Corpse Parts (JoJo's Bizarre Adventure Part 7: Steel Ball Run)
D.R. (Monsters) wielding the Dragon Horn, which allows him to summon and control dragons.
Whoever consume a Devil Fruit (One Piece) will be granted a unique life-long power, at the cost of no longer being able to swim.
Pandora's Box (Code:Breaker)
The Turtles (Mutant Turtles: Chōjin Densetsu Hen) using the MutaStones to transform into "SuperMutants."
MutaStones (Mutant Turtles: Chōjin Densetsu Hen)
The Philosophers Stone (Fullmatel Alchemist: Brotherhood)
Shikon Jewel (InuYasha)
Tetsusaiga and Tenseiga (InuYasha)
Death Note (Death Note)
The Artifacts of Darkness (Yu Yu Hakusho): Orb of Baast, Forlorn Hope and Shadow Sword.
Sailor Moon (Sailor Moon) with the Silver Crystal
Reiki (Tenjho Tenge), in the hands of a special power user, can negate all special powers.
The armor, Eternity, and sword, Instant grants eternal life and deflection of attacks (Pokemon Manga).
The Blade of Olympus (God of War) was a powerful weapon that Zeus forged from the heavens and the earth.
Elemental Stones (Bomberman 64: The Second Attack)
Bomb Elements (Bomberman Generation)
Chaos Emeralds (Sonic the Hedgehog)
Master Emerald (Sonic the Hedgehog)
Sol Emeralds (Sonic the Hedgehog)
Worlds Ring (Sonic the Hedgehog)
Sonic's shoes (Sonic the Hedgehog)
Chaos Crystals (Sonic Boom)
The Master Sword (The Legend of Zelda)
The Magic Armor Gem (The Legend of Zelda: The Wind Waker) grants Link a temporary invincible defense, taking less physical damage. With the Magic Armor Gem itself sending purple-pink energy whisps surrounding Links body, and slightly contouring it. Which also shapes around his hat.
The Magic Armor (The Legend of Zelda: Twilight Princess) makes the wearer invincible.
The Rod of Seasons allows Link to change the very four seasons.
The Harp of Ages allows Link to warp through time itself.
The Phantom Sword (The Legend of Zelda: Phantom Hourglass)
The Lokomo Sword (The Legend of Zelda: Spirit Tracks)
The Goddess Sword (The Legend of Zelda: Skyward Sword)
Super Mushroom (Mario)
1-UP Mushroom (Mario)
Mega Mushroom (Mario)
The Star Rod (Mario/Kirby)
The Mega Stones and Key Stone (Pokemon) can be used to make a specific pokemon Mega Evolve.
By holding a Z-Ring and a specific Z-Crystal (Pokemon) a trainer can make his pokemon use a powerful Z-Move.
The Ray-Sphere (inFAMOUS)
Holy Cross from (Dante's Inferno)
Death's Scythe from (Dante's Inferno)
The Windsword (AQWorlds)
BHB's Gravity Generator (Bomberman 64: The Second Attack)
The Guru uses the Moon Stone he holds to use his mystical powers.
Kazuma's Shell Bullet fins (S-cry-ed).
Jewel Girl (Valkyrie Crusade) can gain a specific power from each jewel (Black Pearl: Exorcism. Hematite: Victory Inducement. etc)
Using the Crimson Hawk Power Coin, Ryu (Power Rangers: Legacy Wars) can tap into the Morphin Grid...
Malachite's Hand (Channel Awesome) was a powerful artifact that grants the user limitless magical power. Because the original gauntlet was old and unfashionable, the stone that powers it was grafted onto a Nintendo Power Glove.
Aeon (Channel Awesome - Suburban Knights) crafted a ring made from lodestone that could reflect Malachite's magic back to him.
Halo/Sydney Scoville's (Grrl Power) seven Light Orbs give each do very different things. One gives her flight, one gives her a very impressive force field, one makes a energy-tentacle… thing, one gives her telepresence, truesight and teleportation, one makes a powerful energy blast, one generates air and of the last one no one has any idea about.