Similar to the Intermediate Human Vocations, the Advanced ones will require you to master some of the other ones in order to unlock them. These are the creme of the crop and you're not going to get any better than these, as they have access to a lot of the upper tier skills that the other classes might only have one or two of, plus there are some exclusive to these classes.
Gladiator and Paladin
The Champion is a class that will be dealing a lot of damage, with a little bit of support sprinkled in for good measure, especially with a 25% boost to strength for just switching to the class and the increased critical hit rate from the passive. They will have access to Thin Air, Helm Splitter, Multislice and Multifists as attack skills, as well as Multiheal, Kazing, Oomph, Kasap and Kabuff as support skills. Gigaslash, learned at level 7, deals a lot of damage (350-400 or so) for 15 MP, but it only hits a single group of enemies. The ultimate ability, Blade of Ultimate Power, is a huge damage attack (500-600 damage) that ignores defense (goodbye Metal Slimes) and can even do more damage if you are equipped with a weapon the enemy is weak against (like a Dragonsbane).
(1) Cheerful Champion
Selflessness, Forbearance, Thin Air, Boulder Toss, Double Up
The Sage is the ultimate magical human class in the game, taking the MP reduction passive from the Sage, up to a maximum of 50% at max level. It has access to all of the Ka-tier attack spells, as well as Hustle Dance and Kazing for support. King Fissure is a more reliable version of Kathwack and Magma Blast is a spell that does around 100+ damage, but it cannot be used at sea. Hellfire is a breath attack, but considering it costs MP to use, it's not too great. Big Banga deals around 300-400 damage, but it costs a lot of MP to use. That Special Summon is similar to Summon, but it can be used more than once per battle and the spirits summoned by it are more powerful.
The Hero is one of the better classes in the game, with its passive being able to regenerate up to 50 HP (at level 8) per round. It has the usual assortment of skills and spells you might find in other classes, as well as access to Omniheal (heal's party HP to full), Gigaslash and even something called Kazapple. The latter takes MP from all of your characters to deal some mega damage, so if a character doesn't have any MP left, then you can't use it. The Hero can also be gotten by using the Hero Heart, but that isn't possible to get until the end of the first postgame dungeon. It is the only Human class that does not have any stat decreases.
The island of Estard sits all alone in the middle of an endless ocean. Until one day, a lowly fisherman's son finds his way into a mysterious shrine. Little does he know that his discovery will change not only his own destiny, but that of the world itself! Join the grand adventure in this 3DS remake of a Playstation classic.
The guide contains the following:
An extensive walkthrough from the beginning to the final boss