Seriously, though, for taunts it could be something like this:
PLD: Emits a flash of light from the user's palm, drawing the target's attention and blinding it for 3 seconds
WAR: Angers the target by shouting at and insulting it, drawing the target's attention and increasing its movement speed by 100% for 5 seconds
DRK: Uses the darkness to cloud the target's mind so it can perceive only the DRK, forcing the target to fixate the DRK for 4 seconds

For stuns?
PLD: Shield Slam: Breaks the target's stance with a powerful hit from the user's shield, interrupting any casting
WAR: Low Blow (might as well keep it)
DRK: Choke: Uses the darkness (NOT The Force. The darkness. Totally different) to crush the target's throat, interrupting the target's cast

For Shirk:
PLD: Uses the same skill as their taunt, but channels it through the target instead. The target emits blinding light, drawing the enemy's ire
WAR: The WAR feigns to have no more interest in fighting, turning his back, pointing at the target and walking off. Insulted by the dismissive attitude, the enemies set their sights on the target
DRK: Like the PLD, the DRK uses the same skill as their taunt, but shifted towards the target. The darkness shrouds the enemies' minds, making them perceive only the target, thus compelling them to attack it.

Yeah, the WAR examples are more silly than the PLD and DRK ones, but I am serious about them. Silliness in class design is not a bad thing when applied correctly.