Equip blood sword. Equip skills that boost dark damage, drain attacks, and power.
Max your Braves.
Cast drain from blood sword, then equip a stronger weapon. The drain effect will remain.
Next turn, rage as many times as possible. The drain effect will ensure your hp does not drain from rage. You'll be able to do many rage attacks.
This class is brutal with someone with hasten world since your turns will increase faster (or with someone with dancer+mimic).
Oh you wanted ninja? Boost the speed/evasion and he'll strike more times with each weapon. 4x turns with two weapons equipped = 8x attacks. I hear it's also good because of evasion/counter but that tactic never seemed to work for me.
Still though, DK's Rage is bonkers since two of them hits upwards to 10x at 9999 HP worth of damage in a turn (provided enemies can't block or absorb Dark damage and you have the HP for it) whereas Dual Wielding only works for basic attacks and basic attacks are subject to accuracy/enemy evade issues. Seriously, if it weren't for the game sporting the NES era Hit mechanics, Dual Wield would be as fantastic here as it has been in every FF game its available in, but as it is, Two Handed is by far the better damage dealing technique since physical based moves run off of only your total P. Atk in your dominant hand. Dual Wielding is only really useful for cranking Int or Mind with dual Wands or Staffs respectfully since Int doesn't care how many pieces of equipment modify the stat.