I HAVE NOT SEEN ANYTHING LIKE YOUR EXAMPLE BUT IT COULD HAVE EVOLVED FROM AN ANCIENT CHINESE FORM. THE OLD FORM BRONZE POLEARMS HAD THE BLADE MONUTED LIKE AN AX OR PICK FOR A DOWNWARD CHOPPING STRIKE. YOUR EXAMPLE HAS A LONG LANCE OR SPEAR BLADE AS THE MAIN WEAPON BUT HAS THE SIDE BLADE THAT COULD BE USED FOR THE DOWNWARD STRIKE.
1. AN EXAMPLE OF A SHANG DYNASTY BRONZE BLADE WITH ONLY THE DOWNWARD CHOPPING STRIKEING FUNCTION
2.AN EXAMPLE OF A CHINESE BRONZE POLEARM HEAD WITH SPEAR AND TWO SIDE BLADES FOR DOWNWARD, SIDE TO SIDE AND THRUSTING STRIKES. I DON'T KNOW IF THIS SECOND FORM IS A REAL HISTORICAL FORM OF ARTEFACT OR A FANTASY ITEM BUT IS THE CLOSEST I CAN COME TO YOUR EXAMPLE. A INTERESTING ITEM PERHAPS SOMEONE CAN PIN IT DOWN FOR YOU GOOD LUCK.
