Plume
Isn't it just two JFs in that combo?
But I agree, about everything with Setsuka requires somewhat strict timing and execution (although I don't think the lack of auto-GI-from-attack is a decider of how hard Setsuka is to use/master).
33B: You must be able to react if it's CH/NH. Then, on CH, you have to execute a somewhat challenging combo (like CH 33B, 2143B:B, 2143~a:B (I think this is the most effective combo)).
1B:B-combo: B&B-combo that requires two hard inputs.
2143~a

Her punisher, unsafe on block and somewhat hard to input. RO very well. Easiest to use as punisher if you are forced into FC on block.
B+K: Not very hard to land the whole string. Can either RO or do ~95 damage. -14 on block(?).
Lows/Throws: Her 1A

A is hard to block, and does good damage, but the range is terrible (also, somewhat tricky to land the JF). Her throws (except B+G) doesn't have very good range (I believe?), but they are all very good when landed. 214B+G can RO well, requires JF, does great damage, great for wallgame. As Plume mentioned, her mixup isn't to scary mid- and long-range, but in close-range, she has alot to dish out.
The thing is, while these strings/moves etc. are somewhat hard to pull off, it's also her B&B, so you will have to execute these very consistently.