Multiple rulings have been made over the years about if/when parry skills can be used to stop healing or other beneficial skills or spells toward another character in weapon range. To settle this issue please consider the highlighted text added to the “Parrying for Another Character” section in Chapter 6 (Combat) of the Rulebook.

Parrying for Another Character

A character can use a martial skill to parry an attack for another character so long as the parrying character is within weapon’s length of the character they are defending.  The parrying character does not take the effect of the attack.

This holds true for spells thrown, or delivered through a weapon or claw, at another character.  A character can parry a spell for another character using any martial parry skill.  However, the parrying character takes the effects of the spell just as if they where hit by it.  The parrying character may call a defense that stops spells if they have one to prevent the spell from affecting them. Spells delivered by touch against another character cannot be parried.

The only exceptions to this rule are the Perfect Aim and True Aim skills.  A character cannot parry these attacks when they are directed against another character.