Balance patches so far have been for all lvl's, since dekan did not have it's balance patch yet I cant speculate about that, I can only say that at endgame lvl the dekan sage conq skill is OP.
I really do hope they change sage to intel and knight to str (skillsets), like they were at the 99 cap etc. Like Eagle said, FFS was not intended as main skill but as a finishing blow that did true damage and could only be resisted or blocked my a magic resist shield (like rangers one). Before WFFS/DFFS you did not see many full vit dekans but mostly str/int ones, I wish to retun to those times :3