To equip this skin, go to the "Arsenal" page, then click on Excalibur's "Appearance" tab. The skin will be under the section labeled "Physique". The skin consists of two parts which can be equipped separately: the Helmet, which can be equipped under the Helmet tab, and the Body skin under the Skin tab.
- This skin was added in Update 12.6, and was only available for a week, from March 25, 2014 to April 2, 2014, and was re-released on March 25, 2015 for Warframe's Second Anniversary. It was re-released a third time when Excalibur was reworked on June 17, 2015.
- It was permanently added to the Market as of November 25, 2015.
- This is the first alternative Body skin to completely change a Warframe's appearance with a different model; previous Immortal Body skins only changed the color patterns on a Warframe. It is also the first Body skin to come with its own exclusive helmet.
- Similar to the Glaive Proto Skin, the Proto-Armor Skin is a near exact copy of Hayden Tenno's suit from Digital Extreme's previous game Dark Sector. Codex hints that the suit existed before the Orokin Age, further hinting that these two separate games may have existed in the same universe, one way or another.
- The only difference the Proto-Armor Skin has to the original are two pouch-like projections on the thigh straps, serving as Excalibur's sidearm holsters that the original armor does not have. This may have been done in order to avoid losing part of Excalibur's silhouette, or just to prevent having to re-code Excalibur's secondary holster positions.
- Proto-Glaive Skin, a matching weapon skin for the Glaive.
- Nyx Nemesis Skin, another Dark Sector-themed Warframe Skin.