That's a shame it's only the two classes, they're the Enchanter and Mage Cannon that appear as enemies in the DLC maps.Japanese website for the game has more details.
- when you finish the DLC story the new units in the DLC campaign will join you in the main quest and you can have supports with them
- two new character classes added. One has your unit use a cannon to fire long range projectiles. The other is a merchant who specializes in items and weapons.