Answer:
Flat as a leaf, round as a ring. Has two eyes, can't see a thing.
Iron on a mammal. Mammal on your feet.
Sharp and long, flag of the world. What is it?
I grow for a surface, even if you cut me. I continue to grow even after death.
It can pierce the best armor and make swords crumble with a rub, yet for all its power It can't harm a wooden club.
A leathery snake, with a stinging bite. I'll stay coiled up, unless I must fight.