[Jim A]

It would never occur to me to use an air wrench on a stubborn spark plug, a blunt force instrument in a delicate location.
Any but the most gentle of re-threading should be done with the head off, a move to avoid.
I have never heard of ratchet jump on anything but the cheapest tool.
A 1/2" drive 6 point socket of the RiGHT size and a a lot of patience, including rocking on and off, is your best bet.
A hard place to get effective heat to, but almost always a help.