The Guardian is one of the two Templar classes.
Guardians lead the charge in the Templar's struggle. Wielding shields and swords, they thrive by drawing groups of Demons in close when they can be punished en masse. Guardians are most effective when overwhelmed and surrounded and immobility can increase their effectivness. Their skill groups consist of: Swordsmanship, Shields, Auras.
The Guardian is the stereotypical tank, built around the use of offhand shields. The Guardian makes for great crowd control, especially since it comes coupled with a handful of AoE skills made to keep the demons on their knees. With Auras, the more enemies they are surrounded by, the more effective the aura becomes.