Basically it boils down to throwing the object with leverage, in terms of a stick or hammer that would mean throwing it so that it goes end over end. You get more accuracy and distance that way, as opposed to just chucking it.
Here's a dandy historical anecdote along the same lines: In WWII, allied troops began using German grenades over their own because they came with a stick attached, which they called "potato mashers." American grenades were spherical and designed that way b/c they thought that American men would have some familiarity with throwing something shaped like a baseball. Turns out, a lot of them didn't and found the Kraut's stick grenades much easier to throw, b/c it was easier to apply leverage to them.