I think in this context, it is important to distinguish between Academic Necromancy and Lore of Vampires. As evidenced by Liber Mortis, these are two very different beasts, even if they produce the same effects, are both commonly known in-universe as just necromancy and even their users often make no distinction between them.
Lore of Vampires is easy and dirty. Every magic user can manipulate dhar directly (and is tempted to do just that in presence of dhar, as evidenced by our Sylvanian campaign), and this approach is exactly that: grabbing Dhar with your soul, grabbing some Shyish with your dhar and weaving them into a necromantic spell. Easy, effective and incredibly toxic (unless you are a vampire, then it's just easy and effective). This is the type of necromancy Mathilde can do just fine right now - and the type of necromancy which warps you into a dhar-damaged lunatic, no matter how fancy your protections are.
Academic Necromancy is grabbing Shyish with your soul and grabbing Dhar with you Shyish and weaving them into spell. It is the style Van Hal used, and this is the style Vlad believed to be safe for mortal practitioners - even after Van Hal went bonkers (notably after years, as opposed to months of practining necromany) which he attributed to ambient dhar poisoning due to all the dhat from necromantic constructs just being around. This is the style which, if Vlad is right, a practitioner with rune of Valaya's Vengeance should be able to practice safely - and which we are unable to use, because our soul is Ulgu.