Answer:
A dragon's tooth in a mortal's hand, I kill, I maim, I divide the land.
What can be as big as an elephant but weighs nothing?
What's full of holes but still holds water?
I make things short but I am pretty long myself
I go up and down at the same time. Up towards to sky and down towards the ground. What am I?
Who makes it, has no need of it. Who buys it, has no use for it. Who uses it, can't see it. What is it?