All Seeing Eye
Eye of Cthulhu
I have trouble seeing cobalt being a defensive armor. True, it's defense value sucks, but cobalt is, and imo should remain, a glass canon armor.
I'll just downgrade it a little bit so it would be less op-ish
Meh, I've seen worse. My only concern: Cobalt's bonus is exactly like Beetle Resistance. Maybe change it so that it resists knockback? You did mention that is has something to do with the Cobalt Shield.
A shield's purpose would either decrease knockback or decrease damage taken . Since we already have the cobalt shield to decrease knockback to 0, it wouldn't be the best to make cobalt's set bonus to do the same.