Probably the most underrated job classes in the game are the Heaven and Hell Knight. I used to think Rafa and Malak weren't that great and wouldn't use them much, but once you get used to them and equip them with the right abilties and items, they are great. I like to give Malak the Earth Clothes, Flash Hat, Magic Gauntlet, and Short Charge and lower his faith to exactly 3. He does about 300+ points of damage with Sky Demon Back at 14MA. Against Juravi and Panthers, it will destroy them in one hit. Furthermore, with the Earth Clothes, he'll absorb Sky Demon Back if the enemy tries to move next to him.

I like give Rafa White Magic and Short Charge, so I can take out individual enemies with Holy, and I'll use her Truth magic attacks against enemies with weaknesses. They key with both of their magic attacks is to target a panel where the effect area will be less, such as the edge of a map or a ditch, like the ones in the Deep Dungeon. Some panels that you target will give you only one effect area, which means the attacks will hit that enemy every single time.