So I made some progress. Dealer said it was safe to whack with my 3LB hammer (all around useful "convincer" tool). With that, I've gotten the pin most of the way out. It's now mostly on the left side, meaning the threaded end is most of the way out and the pin end is now pretty much flush with the ball opening. I need a punch of some sort or similar tool that'll push on the pin while I hit with the hammer some more, or perhaps the air hammer mentioned above, which sounded like a good plan.
Getting the arm off isn't so easy, as the lower end of it has one of the same ball joint setups. There are also some pins, but those aren't a big issue. I did think about removing it.
A gear puller didn't work, because the arms have no flat surface in the area involved. That's really a shame, as the puller would have otherwise made short work of it. If I had a heavy piece of steel with a cut-out to go around the pin, that would surely work. Haven't come up with anything for that yet.