I've used a Dremel with a rough grit sanding head in the past to duck bill a few bats, I started with and old broken one to practice but soon found that if you were gentle enough and patient enough, that it can remove enough wood to make a tangible difference and it also provides with really good accuracy.
To each their own of course, some will say it is a terrible idea, and heck, it probably is, but worth a thought if you are determined to not send the bat away.