Riddles

I can ruin cars and make swords crumble. Yet for all my power, I can't harm a club.

When you need me you throw me away. When you don't need me you bring me back.

I have lakes with no water, mountains with no stone, and forests with no trees.

Two sisters, one dark, one fair. In twin towers dwelling. One from land and one from sea.

Walk on the living, they don't even mumble. Walk on the dead, they mutter and grumble.

What will make the barrel lighter if you put it in a barrel?

He got me in the forest. He sat down to seek me. He couldn't find me, so he took me home.

The poor have it, the rich need it. You'll die if you eat it.

I have a name, but if you say it I'll disappear.

What word is shorter when you add two letters on the end?