So to clarify deflector doesn’t work outside of front arc. It also doesn’t work while reviving an ally. It also doesn’t work against snipers. The description should say “Can block weak ranged attacks sometimes.”
Your weapon isn’t active while you’re reviving that’s why it doesn’t work in that scenario. Snipers are an exception I find wholly intuitive frankly.
I don’t believe it does no. You may have noticed your stamina bar size doesn’t match your weapon when reviving. Same thing happened to Ogryn shield too. Reviving is a unique state, I think it only factors in relevant feats and curio bonuses.
I’m not 100% on those details though, it’s possible it does actually factor in weapon bonus stamina and block efficiency perks
Sniper blocking is actually allowed and will block break with no extra stamina or block efficiencies, but when you use Kinetic Deflection this somehow stops working at all. That much is a bug, anyway. Extra stamina is god on Psyker so you can straight up not run kinetic, you can revive like nuts with just +stamina on a curio and a staff.