This character has an Artificial Limb, Electronic Eye or other prosthesis, and while he's not a full Cyborg--the rest of him is just squishy human flesh--what he does have is far stronger, more durable and just plain better than his former body part. There's only one problem: it keeps getting wrecked. Enemies shoot like there's a bullseye on it, falling rocks gravitate towards it and it falls off at the drop of a hat like the character is some Steam Punk leper. Meanwhile, his natural appendages never suffer more than flesh wounds, despite being made of far less hardy stuff. Often Fake Arm Disarms are used to temporarily bring a character down to normal in a way that preserves the status quo. Destroying the flesh-and-blood arm of a character would gravely injure them and provoke major Character Development, but a prosthesis can be broken or detached without endangering the character and fixed with relative ease after the fight. On the other hand, the character can also Invoke the trope in order to protect his less replaceable limbs, like leaving the prosthesis behind as a decoy while the character escapes. Frequently Justified, as realistic prostheses are usually weaker than the body parts they replace and detachable, making them easy to lose. Also, the strength of an Artificial Limb could make a character be more reckless with it and a weaponized prosthesis would be an obvious target for enemies. Compare to the bloodier An Arm and a Leg. Subtrope of Good Thing You Can Heal.
Hello, Unknown Troper. You'll need to get known to lend a hand here.