"Described as "18th–19th C Spanish or Philippines Naval Dirk"" 
 
Jumping back to Post 1.  
And obviously ignoring the intricate handle, but it does have a slight resemblance to the 1833 French government issue of the Naval dagger (Poignard de Marine), although this had a triangular section blade. 
 
This may explain the above description connecting it to a 'Naval Dirk'. I have never seen reference to a Spanish or Philippine version.  
 
It was part of the Systeme 1833 suite of weapons and came with a leather or metal triangular sheath.
		 
		
		
		
			
		
		
		
		
		
		
		
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