The Dark Knight against Cecil.Dark Knight: I...I am Cecil! The true Cecil!Cecil: You are myself...That is true...the part that has shut itself from the world, once upon a time...But those days are over...You are no longer alone!
If Golbez is not in the party with Cecil, the Dark Knight will instantly kill the party during the first phase and it will be Game Over. If he is, Golbez will take a fatal hit for Cecil. During the second phase, Cecil will regain his stats and abilities and will be able to fight the Dark Knight.
The Dark Knight will use strong attacks. His Black Fang reduces a party member to one HP, and Darkness, which can be dangerous if there is no White Magic user available. He can use Doom, which will always work. He may counterattack magic cast on him with Doom.
The Dark Knight is not a threatening opponent during the second phase, and is quickly beaten with the party's best attacks or Band abilities.