Answer:
What does everyone know how to open but not how to close?
My first keeps time, my second spends time, my whole tells time.
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.
My first is in wield, sever bones and marrow. My second is in blade, forged in cold steel. My third is in arbalest, and also in arrows. My fourth is in power, plunged through a shield. My fifth is in honor, and also in vows My last will put an end to it all.
It happens when something has been cut with H2O.
What language does a billboard speak?