Commoners are one of two base classes available to every unit in the game; the only difference between them and Noble is the 5% Charm growth available to Nobles. Regardless, there is little reason to remain in this class, as the lack of growths does little for any unit, and the HP +5 skill is not necessarily worth grinding out class mastery for.
Commoners have access to various weapon types and even movement types, (such as Mounted, Flying, etc.) that they can advance through via training. Upon reaching a minimum rank in one of these areas they can promote into a base class.
|FE16||HP +5||Mastery Ability of Commoners.|