A tonfa is a forearm length club with a handle protruding sideways. A common claim is that the weapon was originally a handle used to turn millstones. German Wikipedia claims that there are pictures and texts that prove the millstone story - without providing internet accessible sources
There's lot's of uncertainty regarding the origin of the Tonfa.
- "The Chinese and Malay words for the weapon (guai and topang respectively) literally mean crutch, which may suggest the weapon originating from the crutch."
- There's also the story the weapon was first developed as such on Okinawa in the centuries after the Satsuma invasion, however tonfa apear to be older. It is also said that Sai (A type of truncheon) are derived from Okinawan farming implements, which appears to be completely false, so I kind of doubt any story that attests a "farming" background to weapons associated with Okinawan martial arts.
So to answer the question of whether tonfa could be reasonably developed from millstone handles, I want pictures and text of likely candidates for these mills and how a tonfa shaped object might fit in.