Wyrm Wizard and Divine Foci

[magicalmagicman]

If you add a spell with a Divine Focus component to a wizard's spellbook via Wyrm Wizard Spell Research class feature, what happens? Does the Wizard need a Divine Focus to cast the spell? Or can he just ignore it because the spell is now arcane?

[Thurbane]

A divine focus is only ever required when casting a divine spell. If a traditionally divine-only spell is cast as arcane through any means (Wyrm Wizard, Southern Mage, Alternate Source Spell etc.) it follows the rules for arcane spells (including ASF), and arcane spells do not require a divine focus.

Although to be honest, even though I'm pretty certain this is correct, I'm struggling to find an unambiguous rules citation.

Divine Focus (DF): A divine focus component is an item of spiritual significance. The divine focus for a cleric or a paladin is a holy symbol appropriate to the character’s faith.
If the Components line includes F/DF or M/DF, the arcane version of the spell has a focus component or a material component (the abbreviation before the slash) and the divine version has a divine focus component (the abbreviation after the slash).

There's two (loosely related) cases given in the official FAQ document:

Are artificers required to use arcane material components or arcane foci for infusions that simulate spells? What about a divine focus?
No. An artificer is neither an arcane spellcaster nor a divine spellcaster, and thus isn’t required to use a material component or focus that’s normally required only of casters of those types.
The artificer can ignore any component listed as an “arcane material component,” and can ignore any focus listed as an “arcane focus” or “divine focus.” For example, even though the 1st-level artificer infusion identify is listed with M (indicating material component), the artificer need not supply the component as part of imbuing the infusion, since that spell lists the component as an “arcane” material component.
Effectively, this allows the artificer to ignore any “Components” line listed as “F/DF” or “M/DF” (see “Components,” on page 174 in the PH, for an explanation of these entries).

If the divine spell a spellthief steals requires a divine focus, does he need to use the same holy symbol as the original caster?
Not exactly. The steal spell class feature states that you must supply the same focus required for the spell. It’s easiest to rule this as meaning “you need a holy symbol—any holy symbol—for cleric or paladin spells, or a sprig of mistletoe or holly for druid or ranger spells.” Spellthieves are masters at cheating the system; it’s not crazy to suppose they can use another deity’s divine focus to cast a rival’s cleric’s spell.
Of course, if the player likes the idea of his character running around with thick chain of holy symbols and other divine focuses (a la Beni from The Mummy), that’s fun too.