lol.I didnt see Radus's dolphin link before I wrote my last message. Anyway,yes it is a dolphin,or a mutant.Perhaps an unlucky fruit of a pervert relationship of a dolphin and a big fish
If somebody draws a dolphin with flakes,I am sure it can't be because of lack of his zoological knowledge,but he tries to symbolize something..
And look, the creature on Eftihis' yataghan's back is clearly a sea dragon,with a head very similar to the finials.If that sea dragon was made and put there, I think it was the same creature represented by the head on the scabbard's tip as well.
Finally as a mid point of all assumptions,I still think it is a dragon rooted in far east and came to Turkey through Iran,but in western part of Turkey and Balkans evolved to suit naval traditions and preferences which were naturally influenced by western literature, turned to a sea dragon,even to something between sea dragon and dolphin, to symbolize not only a fearsome creature,but -dolphin- as well,well known as friend and protector of men on sea ,and as a personal suggestion of me, perhaps weighing even more towards dolphin, especially in the descending period of Ottomans when they more needed protection and help instead of a fearsome image which was not useful anymore.