Given that other "6-way" wrenches (note "Oil Trades Supply" 6-way wrench photo attached) that include this shape are generally understood to be cap wrenches for oil / fuel / petroleum product tanks , and this one has the kind of "pry" associated with ground-level covers over below-ground features like water shut-offs & the like, I'd vote for "access tool & cap wrench for buried oil tank," and try to find someone who knew how those products were handled in the past in the region where this piece originated to see if my guess was accurate.