if u haven't got some of the secret stuff (celestial weapons, all overdrives, all aeons, etc) then i suggest u turn back. u can get so much out of this game without completing it. if u still can't beat jecht then just stat build inside sin. i would get the things i mentioned above then kill complete the game, tjhen og back for the rest of the secret stuff. this way the end doesn't seem disappointingly easy wen ur stats are maxed ut and it takes 2 attacks to kill jecht!!!