Yustas, could we see a picture of the entire sword. It helps to have context. 
The marking looks very much like a European cypher known as a ligature, three entwined initials often topped by a crown. This seems primarily 18th century affectation, and if on a Cossack sword may be a heirloom or award blade.  
 
All best regards, 
Jim
		 
		
		
		
		
		
		
		
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