I don't know about the RAI, but the RAW is clearly unclear. So I go with the not-obviously-ridiculously-broken interpretation.
Hmmm, upon re-reading, it's not
nearly as clear as I thought, every reference to mental magic could easily mean thaumaturgy except for the one about using spirit evocations with a summoned creature's True Name.
Given that, OK, I think either "weapon rating 0" or "evothaum" (if you allow evothaum for psychomancy to be bought outside of Sponsored Magic) is fine. It still seems a bit off because other supernatural powers don't seem to treat mental stress as overwhelmingly massively better than physical...
I believe there was a post by one of the writers about sleep spells and such in a conflict that definitely suggested that mental evocation was supposed to exist, though.
I've actually heard the opposite interpretation for casters...some people like to use mental stress to deplete their spell reserves. And most casters have a decent Athletics and/or a physical armour item of some kind, in my experience.
In a game in which mental evocation exists & is broadly allowed, mental armor items are probably going to be as common as physical ones.
And, most PC casters probably do, but I wouldn't necessarily think it's the norm "in world". Oh, in something like my Defending the Borders game, they probably would, but that's because at that power level it's barely worth having the combat at all unless the opponent is either specialized for it or ridiculously powerful (or both).
"In world", though, I think combat specced spellcasters are very much the exception (thus, even at the worst of the Vampire War when lowering their standards and drafting people, the WC could only get about 1/20 to be Wardens).
I make mental toughness cost only 1 Refresh per level if you have physical toughness at that level already, which really cuts down on the Refresh bloat.
Interesting... like Sight and Soulgaze kind of synergy? Seems somewhat powerful, but yeah, I don't know how else to deal with the Refresh bloat.