The knight company on shadow horses seems like something that would bottleneck at their ability to get said shadow horses, and unless there's more to that idea I'm seeing it doesn't really add more than 'is a company of mounted knights'.
The shadowhorse knights have been a personal goal of mine for a while, ever since trying to write Soizic's feelings on horses. Also, tying back to the really old idea for a group of knights formed to seek out wizarding candidates, and deliver them safely to the colleges. I thought it would be really cool to cement the dammerlichter's reputation. (The dwarves know her as Azrildrekked, the wizards with clearance as Magister Grey or Magister Webber, the heir to the throne knows her as Godmother, but to the hinterlands of the empire (ie, Stirland and Sylvania) she is still the Dammerlichter.)
But these days, it would be more a unit of far-ranging heavy cavalry, knights built to reach and break raids on caravans that the gyrocopter scouts report. Maybe a hundred bridles, enchanted with shadowhorse and capable of going from dawn to dusk, perhaps keyed off if one master bridle that distributed the spell to all the others. Ie, a unit item rather than a hundred individual-use items. Maybe set them up so they'd grow into the individual use items over tine as use and repetition ground the spell into them, until they could trigger on their own?
That would set it up nicely to transition from a purely K8P unit to a legacy order of knights scouring the border princedoms for any magically talented young, bringing them back to the U-K8P branch of the Imperial Magic Colleges. Secure Mathilde's legacy by giving others a chance to be saved as she was was by the watchman, give K8P a source of magical talent to support their new doctrines and culture, give a purpose to a branch college way out here in the boonies: to scoop up and utilize for the empire's benefit all the border princedom's potential mages.
And it all starts from giving Soizic and 99 of her best magical horses.
Heck, that sort of 'outfit a unit with gear' is the province of runelords, usually, so the dwarves might even be impressed.