To add a card is to place a card in the hand.

“Adding a card from the Deck” is not considered as drawing a card. If your opponent control "Protector of the Sanctuary", you can still use the effect of "Archfiend's Oath" to “add a card”. However, “drawing a card” is a form of “adding a card from the Deck”. If "Blackwing - Breeze the Zephyr" was drawn by a card effect, then you can Special Summon it.

To prevent cheating, when an effect requires you to add a card of a specific type from your Deck, then you must reveal the card to your opponent.

You do not lose the duel if you have no card in your Deck when required to add a card from it.