Descendants of Fianna is a special nickname that the players of The World have given to the conquerors of The One Sin event, Balmung of the Azure Sky and Orca of the Azure Sea. The name originates from a poem posted on the BBS by web poet W.B. Yeats. What most users (and even fans of .hack) don't know is that there are three Descendants of Fianna. Aside from Balmung and Orca, who are named directly in the poem, Albireo is indirectly mentioned as the third Descendant. Later, when Kite defeats Morganna, he gains the title Kite of the Azure Flame, though, it is unknown if he is counted as a Descendant of Fianna.
The Poem
Damage done to the evil shaped one too massive to compare Balmung of the Azure Sky Orca of the Azure Sea together they gallop at full speed. At the depth of my bosom, your names shall remain. You are none other than the descendants of Fianna. Together with the warrior who wears the eyes of the stars.