Answer:
Soldiers fight it but never changes.
Up on high I wave away but not a word can I say.
It could make arrows fly and kites soar. What is it?
You row in one while you float.
Dry though I may be, I am still a sea.
Of these things - I have two. One for me - and one for you. And when you ask about the price, I simply smile and nod twice.