Our idea of a scythe is a rather horrible weapon.
Just try to imagine using it. First, because the blade is towards you, you would have to have a target inside the blade, meaning you have nothing to defend yourself with. Just to swing the blade, you would need to make a wide arc and leave yourself perfectly exposed to being stabbed.
Unlike a regular polearm, you would have no way of keeping anyone away from you because the sharp end is pointed towards you. A person could easily knock the blade out of the way from the blunt side, rush up, and stab you.
Cutting people would be awkward at best because instead of bringing the blade directly down as that would mean you only hit a person with the stick part and not the knifey bit.