Sword Song by Rosemary Sutcliff
"Just go! A man with a sword need never lack the means of life--or death. If after five years you still live and you shall be free to return and take your place in the settlement again, it may be that I shall be able to stand the sight of you."
With these harsh words from his chief, Bjarni Sigurdson, a young Viking swordsman, is banished from his home.