In Slavic mythology, the Raróg (Polish pronunciation: [ˈraruk]), far from a demon, was the fiery falcon. Fire - is the symbol of purity of conscience and mind.
Rarog was illustrated on coat of arms of ancient Slavs. They have chosen this image for blazon, simply because falcon is the only predatory bird that attacks their opponent to the face, without using any cunning tactics. You can still see Rarog on the blazon of Ukraine.