A fascine knife is the same thing as the working tool called a billhook - just a different name.
When you build it with a socket type handle, you can mount it with a short or a long pole for a handle. With a long pole handle, the tool is called a slasher. But the weapon is still then just called a bill or billhook.
Many cultures had/have their variation of these. In the early 1900's, several axe companies made a full-sized axe with that curve "bill" on it - called a brush axe or brush hook. You can still buy them. But they tend to be full-sized axes, and don't have the same "look" as a fascine knife.
And if you do a little study of them over in Britain, there are regional differences in their shape/size. Some have a pronounce hook, some have the hook curved backwards. Some have that straight cutting edge on the back, some don't, and some have a little extende "axe" type blade off the back.
There's a look at some of the variations/varieties of billhooks/fascine knives in the book
Old Farms: An Illustrade Guide by John Vince
isbn 0-517-60556-2 pub in 1982
And the use of them in making hurdles and hedges in
The Forgotten Crafts: A practical guide to traditional skills By John Seymour isbn 0-394-53956-7 pub in 1984
And using them to build fortifications in
Picture Book of the Continental Soldier by C. Keith Wilbur (my copy is from 1969, so it doesn't have an isbn in it)
And a couple of the Shire Album booklets have info, like
#100 Agricultural Hand Tools by Roy Brigden
The style fascine knife or billhook that you made is close to those from Oxon or Kent.
Mikey - yee ol' grumpy German blacksmith out in the Hinterland
p.s. I have around a dozen or so originals floating about - in various sizes and shapes. And I occasionally use some of them, but more often just use my "corn knife" - rural farm version of a machete.