Answer:
You fill it and it empties, A metaphor for plenty, Depending on what half you see, It's either full or empty
A
Passed from father to son and shared between brothers, its importance is unquestioned though it is used more by others.
Made of ten but two we make, When assembled others quake, Five apart and we are weak, Five together havoc wreak. What are we?
What is in seasons, seconds, centuries, and minutes, but not in decades, years, or days?
What do you purposefully put lots of in and on your body, but run away from when you encounter it outside?