Lady Luck is pretty strong. Casually doing more damage than the Dark Knight with a set of cards.

IMO the only abilities on the Dark Knight worth a damn are the passives. Maybe Black Sky. The only other reason you'd use this dressphere is for its defenses and Darkness. I find it pretty boring tbh. (Not going to suggest it ever again =P)

I still have to laugh a bit over how all of the enemies just simply cannot ever hit you after Matador's Song.

Reels aren't random. You got Clean Slate for getting two cherries in a row and Armor Break for one cherry in a row. The game is nice enough to give you all horizontals and diagonals you manage to get which is the reason you keep getting multiple WINs/attacks. The reels aren't too bad since they only have a few symbols before the pattern repeats. With good timing it's not too hard to hit. 777 gives you Shin-Zantetsu (Death on all enemies) IIRC. The real good stuff is on the other reels abilities which have two of the single most broken abilities in the game. I'd almost say it's worth learning to use the reels properly just to get those consistently.

Dud is a pretty hefty price to pay for messing up though...

"Never gonna use Lady Luck ever again"? No way. Lady Luck is great! IIRC there's some tougher fighting coming up next time so I'll nominate Songstress Yuna, White Mage Rikku, Psychic Paine.