Corrected entry: The staff made from the splinter should have shrunk back down to splinter size eventually. When the same spell was used to try to grow the gas can but failed, he accidentally shrunk his brother. The spell wore off after just an hour or so and the brother said that the spell wears off, so should have worn off on the staff too.
LorgSkyegon
19th Apr 2020
Correction: The shrinking effect was the spell going wrong, so it did eventually wear off. The enlargement is permanent.
LorgSkyegon