Answer:
A dragons tooth in a mortals hand I kill I maim I divide the land.
The more you have me the less you see. Shine a light on me and I shall flee.
I am a path between high natural masses; remove the first letter to get a path between man-made masses.
Before I grow I'm small. When I'm old I grow tall. When I die I give a mighty fall.
What word is pronounced the same if you take away four of its five letters?
Break me and I am better immediately set and harder to be broken again.