I also would recommend to clean the dirt on the blade close to the golden decoration, this in order to avoid that dirt getting a negative impact on that decoration ... 
some of my blades were as dirty as yours 
 
please compare ; the first picture is your uncleaned one versus the others ( my cleaned ones in black and white pics). 
 Good luck and thumbs up with your very beautiful yataghan !
		 
		
		
		
			
		
		
		
		
		
		
		
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