is that a ps3 game? if so ill probably play it and beat in under 5 shots max. Megaman and bass is another game that is unfair in difficulty (the gba version at least)
edit- wait a minute i already beat that game ages ago for the ps1, I only didn't mind it because the graphics are fun and nostalgic, the recovery items and limits make it a cakewalk though
Role Playing series have all much tougher opponents then the final bosses if you are interested in real challenges. And not only would you not beat Ruby in 5 shots but you would not beat the underwater weapon in 5 turns. The limits also were nothing special against these opponents. Its obvious to me that you are just a basic player who just beat the game straight through.
And i must mention that another thing that decides how hard a turn based combat game is if you dont level up often. If you just keep progressing the story line and dont stop to grind because you are having a hard time beating someone then the game will be very challenging.