Nightmare:
"Behold the power of a weapon, designed to bring down gods.
It only takes a blink to win a fight.
Seconds to end a skirmish.
Minutes to level a city.
Hours to conquer a kingdom.
A day to end all life on a planet."

Young Icedragon:
"If they are as powerfull as you say, how comes nobody uses them?"

Nightmare:
"With great power comes great consequence.
No regular beeing can wield such a weapon for longer than mere seconds.
No immortal is known to survive their use for longer than a couple of minutes.
This weapon is fueled by soul. Using it means sacrificing yourself.
You either are extremely desperate, or downright insane, or managed to even surpass immortality.
The last one should give you a clue on who might actually use them."

Young Icedragon:
"The Shadow Of The World..."

Nightmare:
"Seems like you begin to understand."