The Scribe is a class that allows more diversity to the magic classes. Normally, all anima users go Mage, all light users go Monk, and all Dark users go Shaman. (Sorcerers help a bit with the dark users). This allows people to take a far more generic class, that isn't so specialized, that also provides a once-per-battle support power to better shield/heal allies (since it disappates on the next turn, after the heal effect, the Scribe doesn't have enough time to leap on it themselves)
The Sapper is basically the exact opposite, instead of creating a temporary fort, it blows them to pieces. They don't debuff the enemy, but they can screw over their defence positions by denying them armor and healing. I made them because normally the Fighter Trainee tree consists of a lot of guys that gain advantages from terrain (be it forest, mountain, or sea) so I like the idea of someone who doesn't conform to the land, but rather shows the terrain who's boss. Their headlamp also make the Torch item (Not to be confused with Torch Staves in the buffing subcategory) actually not shit. I considered making the use of the Torch also restore 5 hp, but went "meh". If you still want that, take a personal skill.
The Archmage was actually the reason I made the Scribe in the first place. On the physical weapons, the Great Knight can wield lances, swords, and axes, so they have all three positions on the weapon triangle, but the mages completely lacked someone capable of this. The closest they got was the Druid, which only gets Dark and Anima. The addition of the Archmage means there's now someone who can wield literally any spell in the game (without resorting to the Bounty Hunter's Omniweapon power). They don't get staves, but their Magic Sigil is improved to last longer and provide more health. Their main power, however, is Master of Arcana, which lets them craft their own spells by exchanging the special properties of one with another. For example, if you're wielding Elwind, you normally get effectiveness vs. Fliers for the wind spell. Now, let's say you MoA mix it with the health-leeching Nosferatu spell. You still use all the stats of Elwind, including its place as Anima on the weapon triangle, but it loses the effectiveness against fliers, and instead drains health. This lets you protect yourself with Warding magic while throwing Meteors, or flip off Monks by sticking dark curses on your Lightning bolts, as just a couple examples.
The Templar is a class that's designed to fill any possible gaps of weapon/magic combos, by letting them wield literally any combo of weapon and tomes (except staves. Just go be a troubadour) as well as giving them Smite and Piety, to do two things. 1) Entice people to switch between weapon and spell, rather than just whatever is most inherently advantageous, and 2) Cause the Templar to switch from being powerful as a physical fighter, to being powerful as a magical caster, as not only their raw damage is empowered, but their defensive capabilities are augmented as well. In addition, their power to place Magic Sigils or to Raze multiple times means they effect the battlefield more frequently. I'd absolutely love to see two Templars fight each other, to see how the constant switches between weapons and spells interact.
The final promoted class, the Wrecker, is designed to be the pinnacle of destructive capability. The Reign of Ruin power not only screws the enemy out of defensive bonuses and healing, but outright reverses them, turning it into a deathtrap, made even more literal when they collapse on top of the unfortunante occupant. The Shockwave power also adds a much needed ability to tell enemies to GTFO, and I can easily imagine an enemy escaping some Ruins, only to be punted back in at the last second. The Wrecker also gains Horseback, which heavily increases their mobility, which is only all more important with Shockwave, to keep the enemy from simply walking right back to their original spot after being thrown. While technically the Wrecker rides a horse, I like to imagine them riding something ridiculous like an elephant.