You have 26 examples of Ability Focus (Spells)? I don't think so. You don't even have 26 examples of implicit exception.
You only have one example of Ability Focus boosting two save DCs, and that's likely the result of an editing error (Fist of Thunder and Lightning) -- the original monster had no feats, so it wasn't an issue that two effects were listed under a single bold heading.
Hypersmurf said:
Your proposed erratum excludes Sp abilities... why? Special abilities can be Sp as well as Ex or Su...
I want to preempt Ability Focus (Spell-Like Abilities), because that's just about as stupid as Ability Focus (Spells) for a critter with a lot of spell-like abilities.
A line saying you can focus on
one spell-like ability would be sufficient; but the first line, the inclusive one, should simply allow you to focus on any (Ex) or (Su) that has a save DC.
But that's a proposal, not a reading.
- - -
Back to the readings: by the doctrine of apparent exception, Int 12 is sufficient for Combat Expertise (PHB-II, page 35); by this same doctrine, Ability Focus does not rely on an ability appearing in the Special Attack line, or the character having a Special Attack line at all (PHB-II, page 51).
So far we have the only prerequisite of Ability Focus not being necessary (and this is separate from my previous argument that it is not sufficient). I'd say the feat is poorly worded, or poorly interpreted by stat-block writers, or both.
Given the above, I'd argue that the doctrine of apparent exception causes more trouble than it's worth. Stat blocks are evil, mang. It's hard to get them right, and probably quite easy to overlook one when editing hundreds. Let's not use them as the gold standard.
Cheers, -- N