I don't see this as analagous; with PA and CE, the character decides to hit a little harder with less accuracy, or use his weapon to fend off his opponent's. The exact mechanics must be known to the player, but not necessarily to the PC.
But the cleric who takes a look at Joe Soldier on the battlefield doesn't know if he's a Warrior1 or a Fighter7, and there's no real way to figure that out in-character. So it is more likely that the cleric would have some method to figure out how many HPs the guy has lost so he can use the best spell available to cure him.
There's no rule for this, but since the PC can't ask, "How many HPs are you down?", and he also needs to be able to know if he should cast Cure Light or Heal, there should be some mechanic for the cleric to figure it out. The Heal skill works well in this function. It might not give an in-game response of, "He's 4/12 HP", but it would let the cleric know which spell to cast; the PC would understand what the Heal skill told him in the same way players understand when they say, "I have 15 HP left".