The definition for "countervail" included this:
"Ultimately, from the Indo-European root wal- (to be strong) that is also the source of valiant, avail, valor, and value."
I wonder if wali (Encarta Encycl. "Wali, honorific title in Islam, given to a saint or wise and holy person, especially to the Sufi masters. In Arabic it means “defender, companion,...") is related?