Along the west coast we call them shake froes.
^ This. Always called it a "shake froe". Mine is in the garage and was originally equipped with the same, useless, upside-down handle as the OP's. NEVER bang on the back of the blade with steel - always use wood.
I hiked upstream about half a mile, found an 8-foot diameter Western Red Cedar
(Thuja plicata) in a log jam, and after about a bazillion crazy plunge cuts (standing waist deep in the river) managed to pirate enough bolts to re-cover the front of the cabin after the Inaugural Day storm in 1994 - had to practically overhaul the entire structure.
Once you start working a bolt and you get the hang of it, you can get tricky.
Below is an example of the work of a master. This shake was salvaged from a collapsed homestead structure on the Olympic Peninsula
originally built in the 1890s. It has a bit of lichen growing on the back side, but that's only because it was laying on the ground. Hard to imagine living in a structure where this was all that was between you and the outdoors. (This example is from an exterior wall, not the roof.)
The cedar shake and shingle industry is alive and well on the Peninsula. Cedar pirates are still pillaging anything they can get to so they can get enough money to buy another dime bag of meth. The last photo in the string was taken along one of
my favorite trails - it leads through a grove of ancient Western Red Cedars - many of which well exceed 8 foot DBH.