This begs the question, when you put a new handle on another tool, is it a tool you made? Typically I would say no. In this case, the function has been significantly altered or enhanced, so I would say it is a new tool.
A lot of saws have a stiffener at the back. These saws extend the handle over the back. Originally the saw plate comes from a HF flush cut saw, or a Zona replacement blade. The Zona tools start out with a back stiffener so that is not a strong modification. The real difference is that the tip extends out and the hand can be right over the blade.
This allows you to use the tip of the saw accurately and it gives you precise control of the end.
Apart from being a very convenient fine toothed saw for small cuts and objects, this saw form can be used to strike a line. With a nicely struck straight line, a larger saw can be angled into the cut and then straitened before going too deep. The end result is absolutely no tear out. The struck line is also much easier to see than the scratch an awl will make and is visible when cut with the grain.
Not every tool modification is a success. This one measures up to the most critical test of a tools value. If you spend 15 minutes looking for a particular tool after passing up several tools that would do the job, you know that the tool you made passes muster.