Caranthir and living armor were great... especially in short rounds. You are comparing it to cards that are not an immediate effect, and (save for The Beast) can be killed by normal removal effects.
Living Armor is a good card because it is an easy to support card, has and almost nobody runs decks with its direct counter, Iris Shade. In addition it has a unique set of in hand and on board immunities (Shilard, bleeding, resets, and lock half of the time.)
Living Armor is bad because it runs tall and got a heavy dose of the nerf hammer. Last year at this time it was a 10s for 10p.
As far as functioning, it works correctly. In the fighting game genre, you have the parry and you have super armor. Both absorb attacks, but you take recoverable damage when you use super armor, no damage when you parry. In Gwent, this system abounds as well, Veil parries statuses and cards like Olgierd Immortal parry damage. Armored Drakkar and living armor act like super armor.
Ironically, i have seen the Artis Sheldon Skaggs interaction in this game once... Sheldon does full board damage before Artis damages him.