Hi Gav,
As Berkeley has noted, it seems these simple peasant scythes were mounted on polearms, much like halberds, and these were heavily used in the 1863 Lithuanian uprising.
Apparantly these infantry scythes were used well into the 20th century as paintings are known from 1906, 1918, and even regimental units known as kosynierzy (= scythe).
On the dark side
the Polish word for death is smierc, and of course the dreaded grim reaper carries a pole mounted scythe........eek!!
Spooky stuff.
All the best,
Jim