Arc
Source Player Core pg. 255
Weapon: The attack arcs to the closest enemy creature within 10 feet of the initial target. If the secondary target's AC is lower than your attack roll result, you deal electricity damage to that creature equal to 1 per weapon damage die.
Starship: The attack arcs to the closest enemy starship within 0 zones of the initial target. If the secondary target's AC is lower than your attack roll result, you deal electricity damage to that starship equal to 1 per weapon damage die.
Starship: The attack arcs to the closest enemy starship within 0 zones of the initial target. If the secondary target's AC is lower than your attack roll result, you deal electricity damage to that starship equal to 1 per weapon damage die.