Answer:
What makes a loud noise when changing its jacket, becomes larger but weighs less?
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 seed am I, three letters make my name. Take away two and I still sound the same.
Thousands lay up gold within this house. But no man made it. Spears past counting guard this house, but no man wards it.
Some live in me, some live on. And some shave me to stride upon. I rarely leave my native land. Until my death I always stand. High and low I may be found. Both above and below ground.
I am your mother's brother's only brother in law. Who am I?