Answer:
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.
Has no feet, but travels far. Is literate, but not a scholar. Has no mouth, yet clearly speaks.
What dress does everyone have, but no one wears?
What binds two people yet touches only one?
Sharp and long, flag of the world. What is it?
What language does a billboard speak?