Based on what you're looking for.
Increasing Defense with a small chance of raising defense, but only by one stage. Corviknight have Bulk, so you don't need to worry so much.
A damaging move of only 80 and also only has 15 PP. But, Iron Head also makes the target flinch with a 30 percent chance.
So, I would say that if you run out of PP, and all of the other moves are non damaging, you should have picked Steel Wing, if the target attacked Corviknight (which was your last Pokemon), you would lose the battle, you could have both.
Other things about Corviknight's moveset
Brave Bird reduces Corviknight's bulk due to the recoil damage, Protect might not be needed in some situations so you could change it to Iron Defense, but Protect is fine. Body Press can deal massive damage with high defense, not Special defense. Don't worry, I know you are trying to keep it's defenses equal.