Each person has one of a number of jobs, which determines their skills, equipped items, and role in a party. They can usually be told apart in battle by their equipped weapons, although without those weapons it's a lot harder to tell what job a character might be.
Twin Blade
These light, fast characters use two smaller swords, one in each hand, rather than one larger blade. They are agile and strike more often than most jobs, but not as heavily armored, and their defense is not as good as some of the more "heavy" classes.
Blade Brandier
These are swordsmen, characters who wield a long but light blade such as a longsword or a katana. They're somewhat in the middle as far as the physical fighters go- not as quick or light as a Twin Blade or Tribal Grappler, but not a heavily armored tank like a Lord Partizan. They have average strength and mobility, and wear light armor.
Edge Punisher
Also a swordsmen, these characters wield gigantic two-handed swords. They are slower then the Blade Brandiers, but each strike is more powerful. Their broadswords are good for cutting down armored foes, and their protection is better than that of the lighter classes.
Lord Partizan
Even more heavily defended then Edge Punishers, Lord Partizans wear the same heavy armor but wield gigantic lances instead of huge swords preferred by the other class. Although they have high physical defense, their defense against magic is generally lacking.
Tribal Grappler
These are the grapplers and scrappers. Characters that use their fists instead of actual weapons. They equip gloves in their weapon slots, and are very quick, with higher HP than most of the "light" classes. They have limited reach however, and use light armor with less defense.
Steam Gunner
As the name implies, these characters use various guns as weapons, and are good at long range attacks. They do have limited ability in close-quarters combat due to their bayonets, but they are more effective from afar, and use lighter armor because of it.
Adept Rogue
These are the jack-of-all-trades. Over time, as they increase in level and complete various quests, they gain access to the various weapons and relevant arts used by other jobs, but because they are leveling different weapons at once, they tend to have access to much fewer arts than a "pure" job of the same level that uses that weapon. Adept Rogues start out with Twin Blades dual swords as their first available weapon type, but can equip heavy armor.
Harvest Cleric
In other words, healers. Harvest Clerics use staves to cast various healing and other spells. Their primary focus is on restoration and support, although over time they do gain access to offensive arts. Harvest Clerics are in high demand, as they are easily the best characters to keep the rest of the party members alive and fighting.
Shadow Warlock
Those with this job are the attack mages, mastering various elemental magic attacks. They use grimories, giant books of magic that they carry open in front of them during battles to cast their spells. Eventually they learn healing magic, but not effectively.
Flick Reaper
Flick Reapers wield gigantic scythes, and have sweeping attacks that are good against multiple enemies rather than a single foe at a time.
Macabre Dancer
A magical type of class that uses status and ability-affecting magic, and is balanced in the other types of magic, healing and attack.
