Krytan armor is an art type used in Prophecies, Factions and PvP. It is only available for the core professions. The hero Olias' starter armor is also called Krytan.
In Prophecies Krytan armor art is used for the collector armor for each profession. Collector armor is available with an insignia slot at armor ratings lower than maximum, and the headgear is also available with an attribute bonus.
The Krytan art is also used for Soldier's armor for warriors. This is available to be crafted with an insignia slot at Stingray Strand and Amnoon Oasis.
In Factions Krytan armor is crafted with an empty insignia slot.