Tieflings aren't weak to holy water. That's Cold Iron for Demons and Alchemically Silvered weapons for Devil, iirc. Maybe it was Cold Iron for both of them.

Yes. Fey have natural damage resist, that are negated with cold iron. Also fey feel extreme discomfort if in contact with cold iron and get a -1 morale penalty to all skills, ab, damage, ac (and abilities I think).

or was it -2.. I can't remember as my beautiful pdf books are missing, thanks to a dying hdd.

I have pondered something similar to this. There's a small but non-zero number of weapons that give Divine damage in the game but aren't restricted to divine classes. Which god's running them, and if it's simply the patron of the wielder, what about the Faithless, and what about when the weapon's used against their favourite things in the world?

I blame Ao?

Just something I chukled to myself today: how does one make divine traps? I mean some cleric blesses a bunch of wires and a plate, and when the adventurer steps on it a deity, sitting on his throne, points a finger down at the prime material plane like Monthy Python and announces with a resonating voice:

Thou has stepped on my holy plate, for which I shall smite thou.

Divine damange isn't positive damage, they're two distinct things. I'm not sure if divine damage, per se, exists in D&D outside NWN? I'm not all too familiar with the core rules of the game.

A flame strike produces a vertical column of divine fire roaring downward. The spell deals 1d6 points of damage per caster level (maximum 15d6). Half the damage is fire damage, but the other half results directly from divine power and is therefore not subject to being reduced by resistance to fire-based attacks.