It doesn't have to be complicated it can be quite simple really.
You can choose to believe in there being a Jeigan AND Oifaye archetype or just one of the 2, it's up to you really.
I acknowledge both Archetypes, Jeigan being the more crappy one and Oifaye being one that CAN make it to endgame. For my gameplay purposes though, there is only Jeigan Archetype since I won't use the Jeigan/Oifaiye unless I feel like using 1 or 2 low tier characters (this excludes the first Jeigan though since there's just no freaking way I'll use him outside of FEDS H5 and even then, it's just for the first few chapters).