Neither should get Steel Wing. It is 70 bp and 90% accuracy. Sure it gives a Defense boost, but that is a 10% chance. Don't bother.
Zapdos has 125 base Sp. Attack stat, so don't waste a moveslot on something like Steel Wing. Heat Wave and HP [Fighting/ Ground] can cover his weaknesses.
Articuno needs to have big attacks to make up for it's lack of offensive power. Steel Wing is adding insult to injury. Hp [Fighting] is better.