Hmm. I have a question about the Artes, and considering the above two pages of argument, I assure you, I don't mean to offend, I am only curious. Perhaps all of this is left up to the players' artistic license? I mean, I can see a lot of interesting applications of the various Artes, both in-combat and out (while keeping their downsides intact), but it's entirely possible you want them to be a bit more rigid, and that's fine.
So, say my Dragoon has mastered Whisper Haste and Flawless Study, allowing her to be some sort of field tactician (physically more frail than the others, but with a highly developed mind; she gives tactical advice and points out weak spots for the others to attack, plots ambushes, all that good stuff, while Whisper Haste allows her to avoid damage during fights). The problem is, none of the Artes have quantifiable durations. So, how long does a Study take? Are certain enemies easier or harder to figure out? Can there be an adapted application of Flawless Study for perceiving group tactics instead of individual abilities? Can it be used outside of combat, for a kind of Sherlock Holmes "pick up on all the details and make deductions" thing?
Same thing for Whisper Haste. Just how long can a Whisperer dodge before the sluggish aftereffects start? Does it have to be "activated", like a spell (and then it always lasts for a set amount of time), or does it have more to do with the number of attacks dodged in succession? For example, my tactician is fighting a single, weak opponent, and she knows she'll only need to dodge a single attack to be able to kill it. Can she use her Haste on that single attack, kill the beast, and be on her merry way, or does she have to be needlessly Hasted for an excess of however many seconds, then succumb to the clumsiness? Basically, the first one means she always has the same amount of dodging time, and always the same amount of clumsiness, while the second means the amount of dodging time correlates to the severity of the aftereffects. Hopefully that makes sense.