The wording for this action, even with the week 5 update, is still leaving me scratching my head. The tricky part is: "If the attack succeeds, the character may spend <A><A> once to add damage equal to the number of weapons involved in the attack to one hit of the attack ." That last bit is throwing me off. What this sounds like to me is that you roll once for all weapons and a success means you hit individually with all weapons, plus you get to add extra damage to one of those hits with two advantages. At least, that's what's implied by the wording.
So, say you're attacking with 10 medium laser cannons (damage 6), and you roll 3 successes and 2 advantages. Would that mean that you inflict 9 successful 9 damage hits (6 + 3), plus 1 successful 19 damage hit? Another possibility is that you only get one hit out of it that does 19 damage.
Any opinions on this, or am I just missing something obvious?