One of my keris has a same little square and I have also wondered what it could be? 
 
-a part of the forging process?, 
-is it talismanic (adding metal of spiritual value) 
-or a previous type of tang/pesi repair 
  
Wondering if anyone knows the meaning of it, and this is often done.
		 
		
		
		
			
		
		
		
		
		
		
		
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