Breath of the Unborn is okay. I don’t personally like it but it can definitely be effective. Spells are necessary in any Arcanyst deck - Arcanysts revolve around spells. Having an Owl on board and no way to buff it up feels pretty horrible.
Trinity Wing does make up for the lack of spells in your deck but isn’t available earlygame (for a giant snowballing Owl) and definitely isn’t reliable every game.