A Cyborg (改造人間 （サイボーグ）Saibōgu, literally Remodeled Human) is a human or other life form that has been modified with machinery and metal for better functioning. These mechanical enhancements can include cybernetic replacements for missing organs or body parts, metal skin for extra protection, and weapons installed somewhere in the body.
Cyborgs have mechanical parts, which are usually visible on the outside. The Pacifista appear to have no visible mechanical parts at all but some are seen hidden underneath their clothes. Aside from this, they may appear as a normal human or animal on the outside. Modifications may be more apparent when they receive wounds as they may leave their mechanical parts exposed.
Cyborgs are rare, as the technology required for their creation is somewhat advanced. Though they have mechanical parts, so long as their brain is not altered in any way, these cyborgs maintain their free will. Cyborgs with their brains modified lose their free will. This leaves them "dead", reducing them to being nothing more than a tool. Cyborgs have no memories or recollections of their past lives.
They can also be made from the corpses of the dead as well as the bodies of the living. The one thing they all share in common is they are still capable of bleeding.
Their mechanical parts put them at high advantage against normal humans, their strength is normally far greater than a normal humans and each cyborg is essentially a living weapon. Those who are cyborgs often have an advantage in battle, as they are more powerful than regular humans in both offense and defense. Amongst the cyborgs themselves, capabilities and power varies per individual design; more advanced models may be superior to less advanced cyborgs. Often Cyborgs can be mistaken for Devil Fruit users given their abilities.
A cyborg with a Devil Fruit power will be placed above the overall capabilities of another cyborg of the same design. Due to the rules of Devil Fruits, copying the exact abilities of one Devil Fruit to another of the same model of cyborg is impossible. However Dr. Vegapunk seems to have found a way of mimicking the powers of the Pika Pika no Mi into the Pacifistas models, putting this particular model of cyborg above the potential power of others.
Another advantage they have is being to able to recover completely after receiving what may be otherwise lethal damage to normal non-cyborg individuals. They can also be repaired, modified and upgraded in ways humans cannot.
Even cyborgs are not without certain flaws that leave them vulnerable, since the modifications that they have received are generally man-made, there are usually some limits to the extent of what they can do. It is later revealed that, given that they were originally flesh and blood, vestiges of their former states still remain within a cyborg's body. Because of that, they can be heavily injured if received internal damage. Another weakness that cyborgs share is that unless they are modified, they do not grow stronger.
One other weakness that the cyborgs whose personality is erased seem to share, is that they, like zombies, seem unable to feel pain, and thus unable to realize when they are in danger, though with their sensors and programming may counteract this to an extent (depends on what their programming is).