Atmo is wrong. Reach just lets you impose a penalty to the person you are attacking with a reach weapon or attack. It does not work on barrier.
From OVA pg 86.
Quote:
Reach (+5) Your attack has extensive reach that makes it difficult to engage you in combat. Perhaps you wield a hefty polearm, strike with immense claws, or just have one hell of a swing. The recipient of this attack, even if it misses, must choose a –1 Penalty to either their Attack or their Defense Rolls against you until your next turn. This Perk may be taken multiple times; for each time it is taken, increase the Penalty by one.
Well when modified with Are of Effect you would roll your barrier dice on behalf of the ally you are protecting. Or You could have them roll it.The important thing is they do not try to get two defenses out of your barrier and their own abilities. If the barrier is used to negate damage to HP by spending endurance, it is your endurance they are spending not theirs.