There are two types of warden in Valhalla. Both are guardians of a sort, but other than that, they are very different.
Wardens from Isadora
On the prison world of Isadora, the Mariedians who have been captured by their former Soulborg servants are kept in fortified dungeons and keeps, where they are forced to do hard labor. Specially designed soulborgs keep guard over them at all times. The commanders of the guards are the Wardens, ruthless taskmasters who spare neither prisoners nor guards. Ever-vigilant, nothing escapes their watchful gaze, and they are swift to mete out punishment to 'lazy' prisoner and careless guard alike. None dare resist them, for they are strong and brutal fighters, well-armed and armored, deadly both at a range and in close-quarters. Those small and swift enough may be able to evade the heavy blows they deal with their bladed guns in hand-to-hand combat, but will not long escape their ranged fire, cutting them down with cold efficiency.
Wardens from Isadora Summoned to Valhalla
Wardens from Toril
Wardens are mighty and powerful defenders of the natural world, fighting to preserve the untamed wilderness. Wardens, like fighters, paladins, and swordmages hold the line for their allies, protecting them from harm. In order to fulfill their sworn duties to the spirits of the natural world, wardens train themselves in the use of simple weapons as well as light armor and shields. Additionally, like barbarians or druids, wardens call upon the primal power of the world they protect, infusing their blows with deadly power.
Like druids, wardens are believed to have the power to polymorph into the shape of wild beasts or even plants. How they acquire these abilities is known only for sure by the wardens, though it is generally believed that they serve mighty nature spirits, who charge them with the protection of the Prime and its wilderness.
Wardens easily make up for their relatively low proficiency in weaponry with several abilities, such as their extraordinary resilience against debilitating effects or injuries. Wardens can take incredible blows and generally have a high degree of vitality that enables them to literally walk through enemy attacks relatively unharmed. Others are instead so aware of their surroundings to the point of anticipating enemy attacks.
Much like barbarians, wardens draw on the primal fury of nature to enhance their capabilities in battle. When allies of a warden are injured by nearby foes wardens will often spring into a feral wrath to defend their friends, calling on nature's power to either hinder their foe or injure them. To further enhance their abilities, wardens use evocations, powers fueled by the nature spirits whom wardens protect and serve, the most basic of which include warden's fury and warden's grasp. Once per day, wardens may use these evocations to transform themselves into wild beasts or other manifestations of the natural world, echoing the druid's wildshape ability.