Combat skin

Combat skins are a type of body armor used by Forerunner combat personnel. The Forerunners had a classification system for combat skins, running from Class 1 to Class 18, and possibly above. According to 343 Guilty Spark, the human MJOLNIR Mark V is ranked on this scale as equal to a Class 2. Combat skins were typically worn by Warrior-Servants, the rate tasked with warfare, but could be used by the dedicated military or security forces of the other the rates as well, such as Builder Security, the security force of the Builder rate. After the Flood threat intensified to critical levels, even civilians were forced to wear combat skins in high-risk areas.

Overview
Combat skin was comparable to, but far more advanced than, the UNSC MJOLNIR Powered Assault Armor. It is first mentioned by 343 Guilty Spark as he is leading John-117 through the Library, wondering why he had brought "such ineffective weapons" to combat the Flood. He notes that the MJOLNIR is ill-suited to combating the Flood, and recommends that he upgrade to a Class 12 combat skin from the MJOLNIR, which is ranked on the Forerunner classification system as a Class 2. On the other hand, Guilty Spark also notes that the MJOLNIR will serve John well when the Flood begins converting Halo's atmosphere, commenting that he is a "good planner". Upon learning that there was a powered armor system six times more powerful than the MJOLNIR, John expressed enthusiasm at the opportunity to wear one.

The Terminals on Installation 00 indicate that other combat skin classifications existed, ranging from 1 to 4, and that there were other suits of a similar nature, such as the battle harness, with its own classification ranging from 1 to 6, and the platform interface skin. Eventually, all civilian personnel were required to wear at least a Class 8 combat skin unless in core areas, and all military personnel were required to wear at least a Class 12 combat skin.

During at least the early years of the Forerunner-Flood War, Forerunner ground troops used combat skins that, while certainly powerful, lacked energy shields, leaving their wearers extremely vulnerable to Flood infection. It is likely that, rather than representing the peak performance of the technology, it is indicative that the Forerunners were woefully unprepared for the Flood onslaught, and were initially slow to adapt their equipment and technology to fighting a purely biological foe.

During the Battle of Installation 00, Guilty Spark can be heard lamenting that John did not upgrade his combat skin. The fact that the Mark VI is more advanced than the Mark V that Guilty Spark had previously encountered and is still classed as a Class 2 may indicate that the combat skin class system is based on factors other than combat performance, or that despite its upgrades it was still inferior to a Class 3 combat skin.

List of appearances

 * Halo: Combat Evolved
 * Halo: Combat Evolved Anniversary
 * Halo: The Flood
 * Halo 3
 * Halo Legends
 * Origins
 * Halo 4