It took me awhile, but I've gotten the following, and they're all amazing in both good and bad ways. They easily wreck hard mode. I'm sure they'd do wonders on lunatic too, but I don't have the patience for a difficulty that turns the game into combat puzzles.
Astra with Waste or Celica's Gale
Astra with Nosferatu
Lethality on a Knight/General
Vantage with Wrath
Counter with Sol/Nosferatu/Lifedrinker
Gale Force. Period
Casting every single rally (+8 to all stats, 12 to lck), and sending Donnel forward.