So I've cleaned off enough grime to see the mark.  It isn't complete, as it appears a portion has worn off.  To me, it looks like the leg and three tail feathers of a bird(?).  In this condition, abstract enough to be open to interpretation.  I'm hoping someone with a good list of known marks can match it up to something.   
As always, thanks for your insights.   
 
Oh, and a picture of the full blade again.  I know folks weren't too pleased with the prior pics, so I hope these prove more useful.
		 
		
		
		
			
		
		
		
		
		
		
		
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