I think I've found a good use for all of her drives.
4D is a somewhat reliable anti-air if you're stuck in drive for example, combos into 28D. You have to remember that combos are only one aspect of this game. The game is "played" IMO at the pressure / mindgame level. Combos just punish your opponent for making stupid decisions.
On block, I suggest finishing the sequence as safely as possible. Overall, Noel's "normal" game is far more safe and easy to use. If you do want to risk it, you'll have to take advantage of all of your options. 214D takes out dragon punches, switch up your attacks to cause frame traps of varying sizes everywhere, and switch it up between overheads and lows. (214A practically is a low)
The cool thing about chain revolver, is that ALL hits can transition into a frame trap (worst-case 28D, most attacks have a better frame trap, but 28D is a frame-trap nonetheless), a low (214A and 6D), an overhead (2D and 6B), a unique "anti-dragonpunch" move (214D), and several guard-crush moves (236D has 2900 Guard Crush. 5C has 2200 and 6C has 2700).
The "strength" of chain revolver is not in any one of these attacks, but the fact that you can do any of them off of any hit.
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Anyway, on block, the safest way to finish her drives is usually 5B -> 236D. Just push them away as far as possible. Not a good idea vs Nu, who can just 5D you on block (13 frame startup on 5D, on your -18 frames from 236D), and good players can IB the 2nd hit of 236D and then rush in with their +23 frames and combo the hell out of you. Stop at 5B sometimes and use 214D sometimes to switch things up as an ender, because quite frankly, they're all punishable. They are just punishable in different ways, and switching things up helps force your opponent to think. (5B -> 236D is a frame trap of size 5. So it isn't safe for them to rush in after a 5B)... Hmm, maybe just stopping at 5B is the best idea.
Also, Taokaka and Noel can punish 5B regardless of when you pull it out (Taokaka crawl, Noel 3C). Hakumen also can, obviously.
I'm somewhat convinced that the only way to safely end a drive chain is from a combo.