It really only means alot if you've played Tales of Vesperia on the XBOX360. But I'll still explain it.
In the game there is a legend about a great catastrophe, there was a pair of siblings, a girl and a boy. One was known as "The Child of the Full Moon, The Child of the Full Moon used her powers to stop the catastrophe, while her brother sacrificed his life in order to save the town's people, he became star that now watches over the world named "Brave Vesperia". It is the brightest star in the night's sky.