Re: I finished reading 5th Edition, Revised
Unless they're being rolled behind the GM screen
If a consistent method is followed to determine whether attacks are Normal or Killing, and that method is openly shared with the players (which, IMO, it should be, if they are to use it), revealing an attack as Normal/Killing will give an insight into the character wielding that attack.
Well, we may have a different understanding of the game mechanics, then. I see the purpose of a Normal/Killing separation to be for, as the text informs us, attacks meant to "kill or maim". In the closest thing I've seen to a contradiction of HERO's "toolkit" approach, the text explicitly directs away from a Killing Attack characters who do not want to seriously injure or incapacitate their opponents. This specifically invokes the intent of a character when determining how to design their powers.
To me, extending this definition through the rest of the game is not only logical but natural to HERO.