The ability to scientifically or supernaturally enhance existing weapons. Sub-Power of Weapon Manipulation
The user is capable of enhancing the performance of any weapon by supernatural or scientific means in order to make them stronger and give the new and/or greater powers. The weapon may have added material to make it less fragile and more durable, or enhanced features to make them more powerful.
May need to have rare items or spells for an upgrade
May be heavier than previous version of weapon.
Takes time to get used to weapon.
May lose advantage of previous weapon before upgrade (ex. new gun has more power and range, but has less ammo and accuracy than previous one).
May not be downgraded again.
May be stolen by enemies and used against you.
Refined Weapon may only be used for certain people
Hermit Gunsmith (Cave Story)
Link (Legend of Zelda); via various weapons
Ghost Rider (Marvel Comics); via Hellfire
Sonic the Hedgehog (Sonic the Hedgehog series); via Ancient Lights
Bunnie D'Coolette (Archie's Sonic the Hedgehog); via robotic limbs
Mario (SuperMario Bros.); via Hammer
Luigi (Super Mario Bros.); via Hammer
Nami (One Piece); via Clima-Tact
Usopp (One Piece); via Kabuto
Brook (One Piece); via Soul Solid
Inuyasha (Inuyasha); via Tessaiga
Sango (Inuyasha); via Boomerang
Samus Aran (Metroid); via upgrades to her Power Suit weapons
Various RPG game characters (i.e. Final Fantasy, Breath of Fire, Legend of Dragoon etc.)
Ryu Hayabusa (Ninja Gaiden); via various weapons
Kazuma (s-CRY-ed); via making contact with the Crystal Alter
Power Rangers (Power Rangers)
Sentai Rangers (Super Sentai)
X (Mega Man X); via his variable weapons system, armor, and limitless potential
Zero (Mega Man X); via his techniques, variable weapons, and black armor.
Edward Elric (Fullmetal Alchemist); via switching automail limbs with a cold climate model (manga/second anime)
Buccaneer (Fullmetal Alchemist); via switching automail arm with different types
Xenovia (Highschool DxD); via Ex-Durandal
Malga Naruse (Horizon In The Middle of Nowhere); via Weiss Fräulein
Margot Naito (Horizon In The Middle of Nowhere); via Schwarz Fräulein
All Zanpakutō users (Bleach); via transformation of Zanpakutō into Shikai and then Bankai form
Dante (Devil May Cry); via devil arms
Jax (Mortal Kombat); via Cybernetic Arms
Haru Glory (Rave Master); via Ten Commandments
Pit (Kid Icarus); via Bow upgrades
Jak (Jak series); via Morph Gun upgrades
Daredevil (Marvel Comics); via improvements to his Billy Club
Spider-Man (Marvel Comics); via modifications to his web formula for special situations.
Captain America (Marvel Comics); via enhancements to his shield
Iron Man (Marvel Comics)
Forge (Marvel Comics)
Moon Knight (Marvel Comics); via Truncheron
Chuck Greene (Dead Rising)
Frank West (Dead Rising)
Sora (Naruto: Shippuden); via Chakra Enhanced Triple-Bladed Claw
Kankuro (Naruto/Naruto: Shippuden); via Sasori Puppet
Angeloids (Sora no Otoshimono); via Pandora
Nightmare (Soul Series); via Soul Edge
Satsuki (Starbiter Satsuki)
Lion-O (ThunderCats 2011); via Sword and Gauntlet of Omens
Slim Cognito (Ratchet & Clank Series)
Travelers Sword (Brave Story); via goddess stones
Nanotech (Ratchet & Clank Series)
Various Weapon' Vendors (Ratchet & Clank Series)
Batour (Wild Arms: Twilight Venom)
The Tessaiga (InuYasha) is capable of absorbing direct youki from and opponent in order to increase its already destructive power.
The Master Sword (Legend of Zelda series) is Link most trusted weapon. Even in its final form, its power can be increased by smithing or magical means...
...in some cases, resulting in the Tempered Sword and the Golden Sword, doubling and eventually quadrupling its power.
The Dragon Sword (Ninja Gaiden) is capable of being upgraded as well being infused with the Eye of the Dragon.
Kazuma (s-CRY-ed) was able to gain more power into his Shell Bullet after making contact with the Crystal Alter.
Whenever his regular formula for his web-fluid is not enough, Spider-Man can create different versions of his formula for dealing with the situation such as a type that can resist fire.
Rachet (Rachet and Clank series) is able to use the Nanomites he gathers from defeated enemies in order to upgrade the strength of his weapons.
X (Mega Man X series) is able to enhanced the his abilities and weapons via various armor pieces he finds throughout the game.
The Morph Guns (Jak and Daxter series).
Many Rangers (Power Rangers/Super Sentai franchise) are able to use enhancement modes such as the Lights of Orion (Lights of Ginga in Japan) to upgrade their weapons.
E-102 Gamma's (Sonic the Hedgehog) upgrades include a laser blaster to lock onto more enemies and a jet booster for hovering.
The Ancient Light (Sonic Adventure series) allows the characters to posses various power-ups for certain levels.
In order to survive a disease, Bunnie D'Coolette (Archie's Sonic the Hedgehog) must have her robotic limbs upgraded with a cooler design.
Buccaneer (Fullmetal Alchemist) gets new automail limbs put in...
for a cooler and stronger design
Mario & Luigi (Mario & Luigi: Superstar Saga) had their hammers reforged to break harder rocks.
Edward Elric (Fullmetal Alchemist) had his automail limbs upgrade to survive cold temperatures, be more durable, and faster against foes (manga/Brotherhood).
Moon Knight (Marvel) upgraded his trademark weapon, the Truncheron, to adamantium with a cable hook
Stark used an Asgardian metal, Uru to repair Captain America's (Marvel: Avengers) shield and made it stronger than ever
Nightmare (Soul Calibur) wields Soul Edge which was a normal sword before bathing it in the blood of countless victims. Because of this it becomes stronger when it comes in contact with blood.It can also restore its strength with every shard of Soul Edge found.
The Sword of Omens (ThunderCats) repels Mumm-Ra when the Eye of Thundera was inserted into it
Lion-O (ThunderCats 2011) used the Spirit Stone to power up his gauntlet and added a laser beam to it
Kankuro added a few weapons to Sasori's body before adding it to his puppet collection
Haru (Rave Master) had the Ten Commandments reforged by Musica when it was broken to make it more durable. Also it changes shapes when different powers were used.
Frank West (Dead Rising/Dead Rising 2) can make some weapons to kill enemies more efficently
Chuck Greene (Dead Rising 2) can invent some deadly weapons so he could kill his enemies more easily
But neither Frank nor Chuck had made some crazy weapons as Nick Ramos (Dead Rising 3). His mechanical skills can turn even the most harmless toys into deadly weapons.
Spyke (Splatoon) can increase the amount of sub-ability slots a piece of gear has in exchange for gold or Super Sea Snails (sitting next to him in this picture).