It's common knowledge that blades are cool. But they can also be a hassle to carry around everywhere. The scabbard might be uncomfortable, and the sword won't simply stick to your back. On top of that, once you finally decide to unsheathe your weapon, you are no longer able to hold anything else in one or both of your hands (or make rude gestures to your opponent). This problem is intensified if the weapon user intends to dual-wield.
The solution: attach the blade to your arm, leaving your hands free to do whatever else you may be inclined to do with them. These blades are often long, vaguely triangular, and taper to a point. Variants include:
Removable arm blade: Attaching the blades to your elbow, wrist, or even the back of your hand.
Permanently-attached blade: Embedding the blades inside your arms, from where they can be deployed and retracted by thought alone (usually employed by robots, cyborgs, and other non-regular human characters).
Blade replaces hand or arm: Replacing one or both of your hands or even your arms with large swords.
The last type is Awesome, but Impractical, as the blades prevent their wielders from performing mundane tasks when not in combat. They are also especially prone to Fake Arm Disarms, as they can be destroyed without gravely injuring the characters. Crafty opponents can also maneuver the wielder into getting them stuck in a wall or something else; and because the weapon is attached to the wielder entirely, letting it go isn't exactly an option. While these drawbacks mitigate many of the practical benefits of having swords attached to your body as opposed to carried, few will have the guts to question your coolness or badassery.
Wolverine Claws are a specific variant. May overlap with Swiss-Army Appendage. Can be considered a subtrope of Cool Sword. Compare its counterpart Arm Cannon, as well as Power Fist. Not to be confused with Shapeshifter Weapons, which are not limited to simply being blades. See also Hook Hand. Compare Combat Haircomb. Commonly a weapon for a Predator Pastiche and/or Wolverine Wannabe.
The examples below are divided into three categories: one, where a blade attached to the arm is a weapon of choice, but not a permanent body part; two, where the blade is permanently attached to the arm and may or may not be concealable; and three, where the entire arm is a blade.
