—In-game description in Fates
Silent Dragons govern over water, manipulate peoples' hearts, and have the ability to see into the future. Silent Dragons breathe vapours of fetid air in order to damage its foes. This class is exclusive to Anankos due to the fact that he's the only pure-blooded Silent Dragon to appear within the game. Descendants of Anankos may have the ability to transform into a dragon, but they won't fully be a Silent Dragon.
The Silent Dragon, in all but one of its forms, is the only Fire Emblem class that uses a 3D model for a map sprite in a game that uses 2D sprites otherwise.