I think Mathilde
might have a smaller chance of miscasting regular BM than Hans the Battle Wizard who started out yesterday, because the biggest factor in her favor is that she usually
doesn't need that much actual firepower in most situations and can rely on other tools at her arsenal. Whereas it is my understanding that Battle Mages have the opposite problem and have more difficulty limiting their magical power to use smaller spells. Unless I'm wrong, Hans has
no choice but to use Battle Magic, severely hindering his odds of survival.
That's more or less why I'm fine learning Battle Magic, and also why it's not really a priority. There is a lot of good we can do that doesn't actually need Mathilde to be an artillery-scale offensive caster. Like, for instance, the Talabheim incident with Alberich: we had a single target to deal with and any of the offensive Battle Magics would have been fairly overkill in an urban environment even if we'd had them. Steed of Shadows miiight have been useful, to get a quick aerial view of the city before coming back down, but it could have also been unnecessarily risky to just looking at him in an emergency.
Do I want to learn more standard Battle Magic? Yes, definitely. But we're currently on a research project and not really expecting any beastherds or Waaaghs to attack Laurelorn anytime soon.
1. Someone would order us to cast what BM we have and to try and dispell enemy spells, because even basic BM is much more rare resource then good fighters
2. The enemies that would be worth assasinating in an Everchosen's army would be along the lines of that Khornate champion who nearly killed us. Except on the battlefield he be either on a nasty mount or in a unit of soldiers. Or both. I don't think trying to assasinite someone like that is safer then BM.
1. On the contrary, I am certain Boney at one point stated that you can't really force someone to learn spells they don't want to learn, and that even if you could it's not worth the risk of having a wizard be upset at you for being forced to learn something they don't want to.
2. Collars of Brass that Khornate Champions occasionally wear don't usually do antimagic offensively. My understanding is that Khorne specifically put his thumbs on the scale there because Ljiljana decided to show up with the entire Kislev pantheon empowering her and Khorne was like 'bet'. That should not be taken as a standard example.