Wow. pretty unique feature.
I have never seen anything similar which is so clearly additional grip for one hand use.  (on ethnographic weapons that is. On new fantasy knives it looks more like a standard to have such protrusions  

 )
	Quote:
	
	
		| I can see better grip, but limited in movement with the wrist. | 
	
 Maybe this is more a tool than a weapon and therefore comfort was more important than free movement...?
Best regards,
Willem