In our campaign (shameless plug for Dresden Files-Dallas on Obsidian Portal,
http://www.obsidianportal.com/campaigns/dfd), I'm playing a faith character and was frustrated with the Devout Words stunt - for one thing, it's not particular to critters with a faith/holy weakness, and 2nd - it's a
block, not a defense (so you have to "set it up" in advance of an attack, rather than being able to react to an attack, like you can with Athletics).
I batted this around with our GM, and this is a first draft of what we came up with to model "Faith as Defense." Comments/feedback welcomed!
Shield of Faith (Conviction Trapping)
Against supernatural creatures that have a weakness/vulnerability to faith, Conviction can be used in conflict situations as a physical defense so long as the character is actively wielding a symbol of what they believe in (a traditional example would be a cross for Christians, but this can vary, as with Harry and his pentacle). If you have at least two True Faith powers, this trapping can also be used against creatures that have a weakness/vulnerability to holy.
Justification – loosely based on the “Devout Words” stunt. This is one of the earliest examples we see in the novels of the power of faith, straight from Harry Dresden’s encounter with Bianca in
Storm Front. Further justification is in
Grave Peril, where even Susan Rodriguez makes a cross work in this way against Mavra at Bianca’s party. Even though defense is more robust than block, 1) it only works on creatures vulnerable to “faith” and 2) it requires a “focus” of sorts. Based on those situational limitations, we think this is just an additional trapping rather than a full-cost stunt.