Lorewise, I'd go for either Ninja or Warrior as the strongest jobs.

As for as weakest lore wise, I'd imagine it'd be either monk or bard. In the case of bard, they are lore wise not fighters by trade, simply empowering the people around them to make up for their own martial deficiency.

Monks are weak because they have to smack the mob like 6 times to have any effect.