I guess what I am thinking of is a double bladed axe with the top blade high enough to cut if you used the axe to poke rather than swing.
I have read that the Russian elite troops love their short shovels sharpened. That would be a vicious weapon.
If I recall correctly, halyards are like pole axes that are meant for use on horse, but I am no expert on medieval stuff, maybe I am thinking of a pole axe.