Shizuri Mugino (A Certain Magical Index) accidentally blew her own left arm and right eye off, so she created a makeshift ones out of her Meltdowner energy before replacing it with a robotic ones.
Seryu Ubiquitous (Akame Ga Kill!) obtained artificial arms prior to her bifurcation, carrying the ability to attach various weapons and a radar to them. She also carries other modifications such replacing her tongue with a gun and an explosive device attached to her skull.
After losing his left forearm during the Eclipse, Guts (Berserk) replaced it with a metallic device known as the Cannon Arm.
Edward Elric's (Fullmetal Alchemist: Brotherhood) right arm and left leg were replaced with advanced automail prosthesis.
Captain Buccaneer (Fullmetal Alchemist) can equip two types of Automail to his body, one which functions like a regular hand that has razor sharp fingers, the other which functions like a chainsaw.
After she was forced to amputate her own left arm to help get away from King Bradley (Wrath), Lan Fan (Fullmetal Alchemist) later received an automail arm as a replacement.
Tōshirō Hijikata (Gintama) had the matsuibō connected to his arm evolve into a Super-Electric Matsuibō RX.
Kōtarō Katsura (Gintama) had his right arm replaced with Hijikata's Super-Electric Matsuibō RX by Kagura.
Umibozu (Gintama) lost his left arm to his son Kamui, and his right to Utsuro, so he eventually replaced both with mechanical prosthetic that can turn into cannons.
Oboro (Gintama) lost his left arm to Kondo and Hijikata, so he replaced it with a robotic one, allowing him to grab onto Takasugi's sword without injury.
Kiru (Karakuri) has a Mechanism as his right arm, allowing him to inject liquid methane into his victims, and then controlling the pressure and temperature to cause them to explode.
After his real arm was cut off by Danna, Phantom (Marchen Awakens Romance) had it replaced with a zombified and much more powerful arm.
Chiyo (Naruto) replaced her left arm with a puppet's, allowing her to install a Mechanical Light Shield Block into it.
Obito Uchiha (Naruto) lost his right arm during the Third Shinobi Great War, so Madara replaced it with the mutated substance from White Zetsu.
Madara Uchiha (Naruto) takes White Zetsu's mutated substance-arm as a replacement to his missing one, simply by linking it at the stump.
Franky (One Piece) has two bionic arms which are installed with a variety of scientific weaponry such as machine guns, rocket launchers and laser beams.
Shiki (One Piece) replaced both his legs with swords after cutting them off during his escape from Impel Down.
Eustass "Captain" Kid (One Piece)
Black Arm Zephyr (One Piece) wields the gigantic Battle Smasher weaponized arm, which contains Sea Stone and powerful ammunition.
Mukuro (Yu Yu Hakusho) suffered such extensive damage when she poured acid onto herself that her right arm has been replaced with a mechanical one, which allows her to slice through space.
Vladimir Aleksandrovich Zadornov (Metal Gear Solid: Peace Walker) has a prosthetic right hand that possesses a built-in lighter, making it makeshift flamethrower and rocket.
As Genji Shimada's injuries left him barely clinging to life (Overwatch), Overwatch offered to rebuild his body in exchange for his help. He was put through an extensive process of cyberization, which enhanced his natural speed and agility and augmented his superlative ninja skills.
During his time as prisoner of the Patriots, Raiden (Metal Gear) was used as a test subject for experiments in exoskeletal enhancement surgery, during which his head and spine were excised from his body from his lower jaw down and grafted into an enhanced synthetic body.