Thanes are professional fighters sworn to protect a clan or tribal chieftain. Serving as bodyguards, companions and the commanders of their liege’s warbands. Such devoted warriors usually come from the leading or noble families of a liege’s country, clan or tribe. Loyalty is the most important quality for them, and they are expected to die defending or avenging their liege. In return for a thane’s faithful service, patrons feed, board and give gifts to their protectors. Thanes from cultures that esteem mounted warriors often embrace the horseman ideal, while those of other societies adopt whatever form of battle is considered most honourable.
The thane is a specialist fighter, much like an evoker is a specialist wizard. Unless otherwise noted, a thane advances in the same manner as a fighter (same Hit Die, base attack bonus, saving throw bonuses, skill points, and so on). When a character elects to take a level of fighter or thane, he may not later take levels in the other class. This prevents the character from gaining the benefits of a 1st-level fighter twice.
The thane’s class skills (and the key ability for each skill) are:
All of the following are class features of the thane.
Weapon and Armour Proficiency: A thane is proficient with all simple and martial weapons and with all armour (heavy, medium and light) and shields (including tower shields).
Bonus Feats: The thane gain bonus feats as normal fighters do. In addition to normal fighter bonus feats, the thane may also select Aura of Bravery, Improved Aid Another and Stalwart as a fighter bonus feat.
Thane’s Vow: At 1st level, a thane devotes himself to a single lord or master. This lord does not have to be an actual ruler, merely any other character the thane determines as being worthy to serve and who accepts the thane’s service. A thane cannot voluntarily change who his lord is for any reason once he has pledged himself to that lord. If the thane’s lord is killed, the thane must exact revenge against his master’s killers or die in the attempt, and should be treated as if under the effects of geas/quest until this mission is fulfilled (this quest cannot be ended prematurely by a remove curse spell). A lordless thane suffers a -4 penalty on all Charisma-based skill checks until he fulfills his vow. After a thane has avenged his previous lord’s death, he is free to devote himself to a new lord and must do so to eliminate the penalty on Charisma-based skill checks.
Source: Dragon Magazine #323 (Page 96)