I just did a Google search for Adze with leather hafting and didn’t find anything. Not to say it isn’t a way of securing head to handle.
There are some really cool tools, if this kind of implement interests you.
Here is too much information.
Griff
Major Categories of Adze
Adze with long handle (foot adze)
The traditional way to use an adze is to straddle the timber or log while holding the adze by its long handle and swing the adze up out in front and center to the users body, then swing the adze down to strike the timber or log. There are many ways to use a long handled adze and various stances or positions for the user to take as the work dictates.
Foot adzes are most commonly known as shipbuilder's or carpenter's adzes. They range in size from 00 to 5 being 3 1/4 to 4 3/4 pounds with the cutting edge 3 inches to 4 1/2 inches wide. On the modern, steel adze the cutting edge may be flat for smoothing work to very rounded for hollowing work such as bowls, gutters and canoes. The shoulders or sides of an adze may be curved called a lipped adze, used for notching. The end away from the cutting edge is called the pole and be of different shapes, generally flat or a pin pole.
Adze with short handle (hand adze)
An adze with a short handle is used for hand work of smaller wooden projects and items. For example the adze with the shorter hammer style handle is used to rough shape the concave of a chair seat.
Carpenter's
A carpenters adze is used for smoothing large surfaces and bringing timbers to rough dimension or for smoothing one or all sides of a large timber. This adze is also used for leveling boards for flooring and for hewing large post and beams for building construction.
The blade of a carpenters adze is typically flat and the weight of the carpenters adze is considerable, the heft in this adze is beneficial for having the leverage and swing in order to remove large amounts of material quickly.
Cooper's
The coopers adze is typically a short handled adze used with one hand. It has a hammer face on the opposite end of the adze for setting the hoops in place over the barrel. This adze is used for barrel making mainly, the 4 chime of the barrel is created with the coopers adze. The chime is beveled at the top and bottom of the barrel where the end of the staves come together.
The coopers adze will have a bolt that is inserted through the entire length of the handle. The cutting edge of the coopers adze is typically 2" to 3 1/2".
Gutter
The gutter adze is aptly named for the gutter shape form that it makes during use. The gutter adze can be used for shaping out canoes, chair seats and any other type of work that requires an elongated scooped out form.
Ships Carpenters Adze
Adzes are used to chip away at the surface of the timber, either to reduce its size or to shape it to a particular dimension. Depending on the size of the adze and curvature of the blade, a skilled adzeman could plane the surface of the timber quite smoothly with little trace of the adze blade.