Here's my recomendation for a new Dark Knight War Cry. (Curtosy of Hellsing Abridged series)

Who are we?
The Nessisary Evil!
Why are we nessisarry?
To purg the world of evil worse than mine!!
And why are we, the Gods chosen few, ordained to undertake this unholy task?
Because no one else will!!!!
And because it's F-ing FUN!!!!!!!