Thanks to japanese discussions, I could search about the origins of some character names.
It seems that フェリド (Ferid) comes from フェリドゥーン (commonly written from the persian : Faridun, so the R in the name is more correct, but not the E), a persian heroe. And in this legend, therie is a guy names Zahhak!
You can see an illustration of the scene in this, where "Faridun strikes down Zahhak": http://www.imagesonline.bl.uk/britishlibrary/controller/subjectidsearch?id=12890&&idx=1&startid=7526
The original story can be read here: http://erga.packhum.org/persian/pf?file=06801281&ct=0
Have this legend inspired the story of Suikoden V, regarding Ferid and Zahhak?