Ahh, shoot. Yeah, this is an oversight from when I tried to give Beastmasters bows. I must have missed moving one ability back to instruments/poles. For now there's no way to teach that ability, but I'll have it fixed in the next update. (Spoiler alert: I can give Beastmasters bows now; thanks Rurusaschi!) Sorry! Sucks that it's needed for a Blue Magick spell, too.
ETA: My notes show that I intended to put that ability on the Ivory Pole, so it might still be there. It depends on how exactly I screwed this up.
ETA: My notes show that I intended to put that ability on the Ivory Pole, so it might still be there. It depends on how exactly I screwed this up.