Thanks for all the replies.
I tried the freezing and magnet trick, but it didn't work. The freezing didn't seem to loosen the bit any, and the bit was too small to generate any real pull with even one of those super strong rare earth magnets. While it was still cold, I tried wedging first a needle then an exacto blade tip into the threads so I could hopefully pry it up a bit, but that didn't work either.
I ended up breaking out the Dremel to excavate a trench from her armpit to the joint, and extracting the bit laterally. Her arm's basically hollow now, and I'll have to backfill it with JB weld and spackle over with putty before redrilling. Not outside my skill level, but a right pain in the mivvonks none the less.

Guess now I'll have to make certain all that was worthwhile by doing an extra spiffy job on the paint & base.
