Answer:
You can tumble in it, roll in it, burn it, animal eat it. Used to cover floors, still used beyond stall doors. Freshens whatever it is placed on. Absorbs whatever is poured into it.
Thousands lay up gold within this house. But no man made it. Spears past counting guard this house, but no man wards it.
An iron horse with a flaxen tail. The faster the horse runs, the shorter his tail becomes.
My first is in wield, sever bones and marrow. My second is in blade, forged in cold steel. My third is an 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.
What comes once in a minute, twice in a moment, but never in a thousand years?
What is always coming but never arrives?