For the most part, it's pretty straightforward, but more subtle things like that can confuse. But it's hard to tell about slayers (Sword skills) though, and a few skills that I can't quite remember...
I shouldn't be one to talk though, given that I haven't even as much as run the game yet >_>; I'm too much of a stickler for wanting to read all the dialogue. I shall contentedly wait, which isn't a bad thing, as it means all sorts of stuff will get patched by the developers, and possibly charts of character aptitudes appearing at some point!
I do wonder how long it will be before an expansion. Considering how the level cap is and the stairs leading to nowhere, and a few other details, it seems like it's a thing that will happen, after all :P
Still gotta finish GoS in any case. I got distracted off of DoD... finally hit the final stage in that today. 204 hours... I got so distracted by subquests in that >.>
...but back on topic, it is curious that a stat debuff would land on her and not be effective. But I lack the in-game quality to experiment with. All I know is that Koishi's base stat debuff spell is so pretty and costs a lot of mp, while other shikigamis have spells that are functionally similar but graphically and delay/mp different... and probably have lesser amounts of debuffing.
She does sound like a problem though, from what I've heard. The only thing that comes to mind which I haven't already heard tried would be attempting an evasion-based counter to her physicals (With ice wall against the water spells, of course), but I'm not sure how realistic it is, especially if Dex debuffs don't do anything. Just because she uses blunt attacks doesn't necessarily mean she has a lower accuracy... but it comes to mind for me.
From a video, though, it seems like she isn't too scary if you just take her on last. But I'm not sure how high of a level this guy is... and the upgraded version is a different matter. I remember hearing about some skill to increase physical resistance, but don't quite remember who it was on...