The description just says "magic missiles or direct damage". Nowhere does it mention augments/hexes. So what is the opinion on this?
Nope. Pretty clear the army book only over-rides general rules when stated. Unless it explicitly says it does, it doesn't.
Kind of answered your own question there. Clearly the wording shows that hex and augments do not work with arcane vassel
I interpret the current rules to not include hexes / buffsand have been playing it as such. Does not bother me too much as my favourite hexes are Iceshard and Miasma, both have excellent range and you have no front arc or LoS restrictions on hexes anyways. Plenty of augments are medium to short range but then hex that enemy