You say this like Windherding isn't trailblazing an entirely unexplored and dangerous endeavor that's constantly risking Dhar backlash
At least with Battlemagic there's an established population of casters that have experience doing it "safely"
Windherding has a single proof of concept under it's belt, and that very nearly went horribly wrong before Mathilde grounded the Miscast
I like Windherding for the record, but at some point it's started to really bother me that Battlemagic in particular gets treated as the unacceptable risk, when Mathilde does all sorts of risky stuff on the regular, that could just as easily have gotten herself killed
She could have been killed with no chance of a save diving down into a boat not all that long ago, had a single roll gone differently
I feel a big part of the difference here is that when Mathilde Windherds --- or works with things like the Aetheric Vitae back before we got comfortable for that matter --- she does so one action at a time and so takes on risks on a case by case basis.
Even the Dawizuforki moment and risks that came with it was something we as players chose, in that moment. IIRC we weren't
quite up to speed with exactly how much fire we were playing with until the roll came down, but it was a thing we chose to do then, there, for that case, and afterwards chose to stop.
I think a big part of the the difference with delving into Battle Magic, by contrast, is a sense that the capability comes with a much more permanent risk that we're accepting into Mathilde's day to day life, or really battle to battle life. It's a set of spells we'll know, and afterwards will never not know. In that, there's a qualitative difference in the risk that's being taken, not just a matter of degree, or aesthetic factors. I'm not sure how many others feel that way, but it seems to be a notable factor for me at least.
For what it's worth and going back to your previous point, if we end up One Rider spell ends up being low battle magic I would be happy to accept the risk, but then, as I said before, the biggest reason I'm voting for a one apparition spell is because it's
the Dämmerlichtreiter, singular. Now that we're going down that road I want to play that theme to the hilt see what comes out the other end.