All of Pacifica’s reincarnations find themselves, for a time, in possession of the axe dropped by the Lumberjack ghost. The time and method varies from incarnation to incarnation; Orion received it from Alcor as a wedding gift the day he married Mizar, and bore it throughout his life, while Helen found it in her attic, having apparently just transported itself there by unknown means, and lost it the next day, shortly before the cult she was a part of made the lethal mistake of calling up what they couldn’t put down.
Dipper’s not sure why, exactly, it happens; there’s no obvious spell or enchantment, any involved beings either don’t exist or are very good at hiding themselves. In the end, it just seems the will of the universe.