Shivering touch is an extremely powerful spell, which also has some serious problems with its wording/editing. Between the two, many DMs ban it. This may be your best choice.
About shivering touch’s damage
Shivering touch gives the spell a duration, as you note, and likewise, as you say,
[...]
- Ability damage is persistent, being removed at 1 point per day, not all being removed in 1 round per caster level.
Damage cannot have a duration. It makes no sense within the system; damage is inherently instantaneous. That means we’re left grasping at straws trying to determine what it means.
Is damage with a duration implicitly a penalty?
- The spell has a duration, and so the Dex damage isn't really damage, it's really a penalty, and thus wouldn't apply.
This is a no-go, by RAW. Shivering touch says it deals “damage,” so RAW that is what it does. It uses “damage” consistently, including the primary spell description. The word “penalty” does not appear at all, so there is no RAW argument that a penalty is what shivering touch applies. “Damage” and “penalty” are separate things in 3.5e, and there is no way for one to implicitly become the other.
Now, as we agree, “damage” with a duration doesn’t really make sense. Penalties have durations, so that would make sense, but it requires ignoring the consistent use of the word “damage” in the description, and that’s not something compatible with the idea of a RAW interpretation, since “damage” is the rule that was written and “penalty” is not.
What about comparison to ray of enfeeblement?
[...]
- Ray of Enfeeblement was originally worded very similarly, and was later errata'd to being a penalty instead.
Not quite. No errata published by Wizards of the Coast tells us to change the wording of anything relating to ray of enfeeblement. Instead, what we have here is that ray of enfeeblement uses “damage” in its summary description, but the primary source on what it does, the actual spell description, uses “penalty.” Errata comes in here because it tells us how to handle such a discrepancy. Officially, RAW, the use of “damage” in the summary is simply an error, which the errata rules instruct us to ignore in favor the primary source, the spell description. Shivering touch does not offer us that, because it never uses the word “penalty” at all. RAW, the similarity here isn’t remotely close enough.
What else could it mean?
So what does a damage spell with a duration mean, RAW? That’s anyone’s guess.
We do have some examples of damaging spells that have durations, though. Primarily, there are damage-over-time spells, and some people do make arguments that RAW, shivering touch doesn’t just deal damage, but it does so repeatedly each round over the duration. (No one is arguing that this makes a balanced spell, of course, since it blatantly does not.) The problem, of course, with this argument is that those spells always say that the spell deals their damage “per round” or similar, and reading in an implicit “per round” to shivering touch isn’t really legitimate, RAW. Even if it were a damage-over-time spell—and there isn’t any real evidence that it’s supposed to be—the frequency of the damage could easily be something other than once per round (which would be highly unusual but not unprecedented, while assuming “once per round” without it being stated explicitly would be unprecedented).
A somewhat more common argument is to say that the duration doesn’t apply to the effect on the target at all, but rather to the caster. That is, so the argument goes, for the duration, the caster has this touch attack they can use repeatedly, by analogy to chill touch, which likewise has a duration and deals damage. But like various damage-over-time spells, chill touch is a problematic precedent because chill touch explains multiple touches explicitly; shivering touch does not.
Still others take a similar tack, but refuse to read in an implicit multi-touch ability, claiming instead that the duration applies to the spell’s charge if you choose to hold it. But that isn’t explicit either, and as far as I know, nothing in 3.5e limits the duration of holding a spell’s charge, explicitly or otherwise, so there really isn’t any precedent for that.
Common non-RAW rulings and responses (IME)
Most, in my experience, just write the whole duration off as an error, and treat the spell as having a duration of instantaneous. Or they write off “damage” as the error, and houserule the spell to apply a penalty. Neither of these is RAW, but rather an attempt to implement an assumed intent, or to provide better balance or gameplay. The suspicion that often fuels these approaches is the thought that what probably happened here is that the spell was originally written one way, and then changed to the opposite, except that parts were missed.
Problem is, we don’t know which way such a change was going. As a penalty, the spell is worthless. As damage, the spell is overpowered. Did they realize the spell was overpowered, and nerf it by making it a penalty—not realizing that made it useless? Or did they realize it was useless as a penalty, and change it to damage—not realizing that made it overpowered? Neither result is good, though, so maybe it doesn’t matter which they meant. This is why so many people end up banning it: we don’t want an overpowered spell, but including a uselessly weak spell doesn’t really offer any value to us either, so why not just ignore the headache and just skip the spell altogether?
About Cold Spell Specialization
- Unless specified otherwise, "damage" refers to hit point damage, not any other kind of damage that the player might try to twist in.
Unfortunately, you’re on very shaky ground here, too. Ability damage is considered to be a type of damage, and in fact Complete Arcane goes so far as to make a special exception for the purposes of sneak attack (sneak attacking with a spell that deals ability damage adds negative energy damage from sneak attack, rather than more ability damage). It’s unlikely this was intentional, but it is consistent and it is RAW.
Still, generalizing Complete Arcane’s sneak attack rule—while not RAW—is widely seen as a fair and valid way to handle the situation. That said, it has problems here too: Cold Spell Specialization is a pretty garbage feat unless you can get it to apply to something better than hp damage, because the numbers are so small (and, in most campaigns, the conditions are so awkward). Honestly, I have a problem with shivering touch itself, but not with Cold Spell Specialization potentially applying a bit of extra ability damage.
