I have seen other bugis in the NL wrapped with simple rope before (there is one for sale right now , not mine, but I won’t post a picture) , if there is no notch rope would slide off, maybe this was meant to help a toli toli to stay in place (would have been invisible). 
 
This is another one witha simple Toli Toli which may have been adorning a kris like this ( from a museum collection)
		 
		
		
		
			
		
		
		
		
		
		
		
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