This is a pretty fun idea for shaping character personality and advancing their development at the same time. Let's see... this campaign spans an impressive sixteen updates, a full third of the quest, so it would be a mistake to draw only on the most recent handful of events when considering what Mathilde has learned/come to believe over the course of the war, even if the big finish will likely have the biggest impact on her for obvious reasons. Let's check back and see how she participated and what she might believe as a result.
In the
Brauzeit, 2475 update she and Van Hal both ran around the Haunted Hills hoping to find some reason that the undead were being stubborn and ultimately found that it was just a matter of difficult geography which the line troops were handling just fine. In
Ulriczeit, 2475 this was followed up by investigating Gustav's work on the Blasphemy of Blood and finding that yes, he had in fact done a fine job of pulverizing it and double-checking his performance was a colossal waste of her time. Between the two of these I could see her learning a powerful lesson about sometimes being completely unnecessary and needing to stand back, let professionals do their work, and have faith in their skills- a lesson which, to jump forward a bit, she put to use in
Assault on Drakenhof, Part 7, where she literally sat on a cushioned chair for days on end while letting the army do their thing, stepping in only when she could provide critical observation which she could reasonably expect no one else to be able to discern (locating the building ritual so that the dwarves could blast it). This lesson would be something like "Focus on what only you can do", or "Everyone should tend to their own tasks".
In
Pflugzeit, 2476, Mathilde spoke with Countess Gabriella von Bundebad, where this exchange occurred:
"What are your plans in this campaign?" you ask.
"Plans? Why would I have plans? The hills are safer for my subjects to graze their herds in, and my neighbour to the east is soon to get a rude visitation they thoroughly deserve. Doing nothing is serving me quite splendidly."
There was some other stuff about her being a vampire and probably plotting, and Van Hal talked about that bit later, but it's the "why would I do anything" that strikes me as the part of this that Mathilde might really walk away from this campaign having taken to heart. von Bundebad, if what she said and Van Hal said about her is to be read into, is probably a vampire who didn't particularly like the other vampires. Presumably she didn't care for Van Hal or the Stirlanders, either. And when they went to war, the leaders of both sides died (probably, the vampire Countess could still crawl out from under some rubble), horrific casualties were taken, Castle Drakenhof itself was shattered... and who was the greatest winner, in the end? There's a reasonable argument to be made that it's Countess Gabriella von Bundebad, who did nothing. I could see that being taken as either a powerful lesson ("The right inaction can serve better than action") or a terrible trauma ("Focus on one enemy leaves another free to grow strong").
In
Nachgeheim, 2476, Mathilde joined the battle against the Singing King. She admired the organization and delegation present among the military staff, as it was her first exposure to it. Interestingly, the Singing King was caught after killing a bunch of greenskins, then was defeated by the Stirlanders, and that defeat allowed for the easy alliance with the Throng of Zhufbar. It feels to me like there should be a lesson to be learned there- enemies defeated/weakened other enemies so that we didn't have to fight them, and the defeat of those enemies allowed the acquisition of friends; that's a powerful statement particularly considering how utterly essential the dwarves later proved in the campaign. If they hadn't joined up here, it's no exaggeration to say that Castle Drakenhof might not have fallen, and certainly taking the town would have been much uglier. Also of note is the truly exceptional double-crit spellcasting that Mathilde pulled off with Kasmir here, where the whole was most certainly more than the sum of its parts- but I'm not sure how to turn that into an internalized lesson. Heck, from the fact that in spite of their star turn a third of the army was on the casualty list means that she could well pick up a damage like "no heroism can save everyone"- certainly nothing in her later experiences would contradict it.
The bulk of the lessons/damage to be drawn from the Assault updates are being brought up already, either in the defaults or by others. A few of my own suggestions, though:
"Subtlety is life", or conversely, "Stand out and die". Enemy spellcasters, identified by their slow and prominent ritual magics? They're just marking themselves out for artillery. Van Hal and Mathilde's doomed charge, drawing so much attention to themselves- if they had stayed in the ranks... well. The Singing King was noted to have completely overlooked the casters at Van Hal's side right before their combo-spell went off, and we saw how that worked out. It's no exaggeration to say that Mathilde's greatest successes in the Drakenhof sequence were when she didn't put herself forward and instead kept to the command tents and artillery batteries- and those who did, well. All those slayers, greatswords, and Markus died in valiant, doomed charges into the heart of the enemy while the artillery won the day by being quietly moved into place until they could decisively strike.
Van Hal spoke his last words to Mathilde, as she stood by his side. They were:
"This changes nothing; Drakenhof will fall. But should I fall too..." he hesitates for just a moment. "In my travelling gear, which should be around here somewhere if the attendants have been doing their job, there's an iron strongbox. It opens to any key as long as the password is spoken: Senthoi. I've faith you'll know what to do with it."
She could draw
so many things from this, and as last words they're a very appropriate choice for inspiration as something that would leave a real emotional impact on her. Many of them could be quite double-edged, too. A couple suggestions: "A powerful will can succeed even after death." "The
Liber Mortis is Van Hal's last gift to me."
I found the Ranald sequence powerful, enough so that I'd be unwilling to vote against anything raging at the gods in general rather than Sigmar in particular- sure, Ranald didn't heal Van Hal, but it's not terribly reasonable to have expected him to; his priests don't even get healing spells as far as I know. Having a literal god to show up and give you a physical sensation of comfort during your time of anguish is pretty incredible, though, and between Ranald and Launy the Barazul I kind of feel like Mathilde had people there for her when she most needed them, and even if they couldn't actually do anything to solve her problems at least she wasn't alone. But I don't know that either of those is likely to have been etched into her personality rather than merely mitigating the damage done.
Mathilde saw or at least saw the evidence of multiple casters blowing themselves up in this campaign. She also saw the Amethyst Patriarch go down to some unknown because he poked it. Further, she had a serious miscast while trying to learn the Invisibility spell that she may well have survived uninjured only because of Ranald's Blessing. I would not be at all surprised to see her develop some kind of magic-related damage because of these factors and her ability to survive a truly incredible physical confrontation and power through wounds afterward; "My magic will kill me, one day". Considering that she's Brave I'd expect the results of that to be more of a fatalistic/reckless acceptance than overcaution, though.
This campaign's major battles, except for the last against Castle Drakenhof, all had fairly horrific casualty figures. Between that and the serious hero casualties I would not be surprised to see a damage like "The road to victory is paved with corpses."
The Castle Drakenhof battle itself demonstrated something else pretty well- it had a ton of nasty enemies inside, but they never got to engage and were shattered piecemeal even though they had plenty of warning- if they'd emerged and formed up the moment smoke started rising from the town instead of letting us entrench around the castle we'd have had a very difficult fight. They lost themselves that battle through their own foolishness. A lesson to be learned there is something like "force is worthless if not brought to bear".