Almost nothing in BRINK will instantly kill.
Except for sticky-grenades and (possibly) backstabs.
This is just a false statement.
The only thing the devs have said is that,
"No GUN, by default, can kill in one hit."Grenades are not guns - neither are knives, and we know a knife will kill an unbuffed Light in one hit.
If a knife can kill in one hit, I fully expect a grenade to ruin your day.
The only grenades I can possibly see not killing in one hit, are grenades shot from GL attachments, and
maybe from regular GL's as well. The chance that a hand grenade will
not kill you in one hit, is slim to none.