I mean... Arguably, Mathilde didn't learn that lesson. She instead learned the equally acceptable one of "know where and when it is safe to brag and/or flex, and when you do, go full hog to satisfy your impulses about all the things you couldn't brag about". So the tactic failed.
They Grey college being what it is, I don't think they'd ever consider "proper use of good judgment" being the lesson a student takes from their instruction as a failure.
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On a related note...
Regarding Eike's induction and rituals to the effect: I have a thought on what we could do. Eike right now wants to be a lot like Mathilde, and it struck me to wonder what theme would allow her to play into that.
At her graduation to her journeymanship, Mathilde became embroiled in a plot, as a spy; Mathilde's lord magistership inducted her into a great and terrible secret of the Grey College; Her Magistership itself by contrast contained no great and terrible secret but she did learn of Skaven shortly after, and the Vitae not so long before.
Out of three on screen advancements she learned a secret not each time, but often enough to be noteworthy.
Perhaps Eike's induction should also be entrusted her with a secret? Both to help bring her in, to gauges her good judgement and suitability in certain things, and depending on the nature of the secret, perhaps help her get through her known readability her Diplomacy.
Ideally, a secret we can handle being spilled perhaps, but one that, on some level,
matters. Enough so that a teenager will sense she isn't being talked down to, but genuinely entrusted with something.
The first thought that comes to mind is AV and the many outcomes of revealing it, and how it will become more difficult to hold off the reveal once the great ORBing happens but whether it's
suitable is beyond me.
But all in all, yeah, regardless of
what secret, I am seriously considering the worth of her having
some secret as an initiation rite.