Answer:
Longer than a decade and shorter than a milennium
I occur twice in eternity. And I'm always within sight.
What is it that you ought to keep after you have given it to someone else?
Glittering points that downward thrust. Sparkling spears that do not rust. What is it?
Almost everyone needs it, asks for it, gives it. But almost nobody takes it.
I am a room that has a roof but no walls. What am I?