The Black Knight (漆黒の騎士 lit. Jet Black Knight or ダークナイト lit. Dark Knight) class is a combat physical class that is exclusive to Fire Emblem: Radiant Dawn. The personal class of the character of the same name, the Black Knight class is armed with Swords and Lances as its weapons of choice, although it has a tendency to wield the former as opposed to the latter as the sole member of the class has the legendary Alondite sword.
In the Black Knight character's original appearance in Path of Radiance, the class that he assumes is a unique version of the General class with higher stat caps. The Black Knight wields both Sword and Lances in this title, and the occult skill assigned to him is Luna.
With the onset of Radiant Dawn, the Black Knight is outfitted in a class that is eponymously named after him. Similar to its predecessor, the class also wields Swords and Lances. The Black Knight class bears a close semblance to the Marshall class, not just due to its choice of weaponry (save for Axes), but also because of the fact that it learns the Eclipse mastery skill when the necessary requirements are met.
The class description in Radiant Dawn states that the Black Knight is able to learn the Luna mastery skill, a skill that he is granted in Path of Radiance as his occult skill but does not have access to in Radiant Dawn, it having been replaced by Eclipse. This error could possibly have come about due to confusions arising from the localisation process; Eclipse is known as Moonlight (Luna's Japanese name) in the original Japanese version.