
Given it costs 1, you'd have to succeed by 4 in order to save 3 resources and break even w/ E-cache. You'd also need to have an item that costs at least 4. You'd probably also want to have the resources to pay for it even if you only succeed by 0 or 1.
You do save 1 action and avoid attacks of opportunity so there is value in that, but it may not be enough to make it worth it when looking at it purely in regards to economy. Where it could be good is using it in combination with events/skills that have additional non-damage effects.
"Throw the Book at Them!", Act of Desperation, Cheap Shot, Grievous Wound. All of these could be good events with this.
Stunning Blow can still evade. Long Shot says "does 1 damage" not, "deals +1 damage" so you can still get some.
Zeal being used for the automatically success means that you can ensure your item is heavily discounted.