Right now, power cards don't inform the player of their brutal weaponry; the closest we get is the weapon card, which simply says "brutal" but not "1 or 2".
I think that instead of reading:
Lightning Execution Axe +1: +8 attack, 1d12+1d8+5 damage.
It should read:
Lightning Execution Axe +1: +8 attack, 1d12 [brutal 2]+1d8+5 damage.