I conjecture that the whip was missing a little round ball on the end, or the ball was too tiny, or scratched. The photo seems to confirm this. Charge density on a metal surface will be much greater if the surface is highly curved, like a sharp point at the end of a whip, or a gouged place on the ball. A corona discharge on the sharp end is very common (because the charge density is so high), and it has two major effects:
(1) It serves to dissipate the charge into the air, ionizing the air. This is very useful on, say, "lightning rods" because the rod, connected to a good ground and surrounded by conductive, ionized air, provides an easy, nominally safe path for the lightning to reach ground. Usually it also reduces the voltage gradient in the surrounding volume so that lightning won't strike there anyhow (which is how lightning rods are supposed to work); and
(2) If the rod isn't grounded at the bottom, it still ionizes the surrounding air, providing a nice path for the lightning, which hits and vaporizes the rod and (usually) whatever it's connected to. You perhaps got lucky.
The ball also makes it less likely that you'll lose an eye by stabbing it with the end of the whip when working around it. Being stabbed in the eye can ruin your whole afternoon.
I'll bet that nearby CB antenna has a half-inch (or bigger) ball.
And here I once thought that little ball was mere decoration.