Boss Gitsmasha said:

Because the Grey Knights and the larger Ordo Malleus would never make a mistake out of circumstance, hubris, prejudice, dogma, stupidity or habit. Their incredibly pure pureness makes everything they do pure and just and pure, after all!

And they would definitely never try to massacre Inquisition agents because they "know too much", after deliberately arriving to late to "help" them. That could never happen! Nosiree!

Anyway; I never implied that you could parry bullets, that has not been thing since the Inquisitor tabletop game and other older lore. What you can parry is grenades, it's just a shame you can't influence the scatter direction or add your SB to the distance.

Azraiel said:

This gets dangerous when two characters both start deflecting a grenade back and forth at each other. "Grenade Tennis," they call it.

Back on topic, though, 40k has always treated the Rule of Cool as more important than piddly things like continuity. Allowing wards on lighter armor isn't likely to be a balance issue, so I see no reason not to allow it if you think it sounds awesome.