Answer:
The sharp slim blade, that cuts the wind. What is it?
Look into my face and I'm everybody. Scratch my back and I'm nobody.
People are hired to get rid of me. I'm often hiding under your bed. In time I'll always return you see. Bite me and you're surely dead.
The older they are the less wrinkles they have.
Two in a whole and four in a pair. And six in a trio you see. And eight's a quartet but what you must get. Is the name that fits just one of me?
What did the piece of wood say when he saw the screwdriver and screws approaching?