For Discipline of Divine Wrath, it doesn't seem very likely that the Oath bonus would be unusable on the first round of use. Except for rare circumstances, you are going to use the Oath right before you attack, and you aren't going to activate the Oath if you know it will be useless. And that is the round you are likely to be using your best attack and action point, if you are so inclined.
It is only the following round where you really face the risk of being pinned and unable to activate the Oath bonus.
That's true for the Discipline of Divine Wrath, so it works that it is largely a two round power.
I was just brainstorming about how you might make Hero of the Faith weaker than it currently is, but distinct from DDW. Only allowing the Oath to work for one turn makes it seem weaker than DDW, but the flexibility of being able to put the Oath on the target early, and use it later, seemed like a good counterbalance. That way, you could use the minor action whenever you had it free, leaving you a minor action on the turn you "redeemed" the oath (in case you needed to activate some nova power, or turn on some magic item).
It also allows you to "call out" your foe in the beginning of the combat, and 'denies' the DM the ability to plan for the oath's effect (for the monster affected). If you throw down DDW, then the monster (assuming it is intelligent) knows to use any powers it might have to get away, or to bring an ally adjacent. If you let HotF last for the entire encounter, even if it only works once, the monster can't be sure about a "safe time" to be adjacent to you.
It was just a suggestion for a rewrite, as I think Hero of the Faith is clearly an outlier on the "useful multiclass feat chart" right now. I wager it will be nerfed, but I really wish I knew
how it was going to be nerfed, because I'm introducing a new character, and some version of this feat (that gave me at least one "double roll" and my choice of Avenger skills) would really fit the character. However, DDW just doesn't work, as this guy would have NO training in Religion.