Yes, the FAQ info is a condensed form of the Dius Fidus guide.
And after 10 years we STILL can't replicate where people claim to have somehow added poison before the other damage types of higher priority - and the devs claim it isn't possible.
Do note that the big danger of crafting with a metal beforehand is that the Runic chance for elemental damage does take precedence over the metal type (the runic chance is applied, then the metal type works on whatever physical is left over), so it's possible, for example, to be making bronze Silver-etched maces, hoping for a 100% Fire weapon, and end up with 100% cold instead from the runic.
Elemental damage is a "Boolean" property from runic/loot generation. It's either present, or not present. When it counted as a property, 10% cold, 90% physical was counted as 100% intensity every bit as much as 100% poison would be. Of course, now it's considered a freebie, but that all or nothing aspect still applies.
So ANY runic capable of crafting a weapon can produce a 100% (one type) weapon. Some people last week or so were trying to claim that low-end fletcher runics couldn't create 100% "intensity" elemental damage (itself a misunderstanding of how the property works), and I went and proved them wrong by using an Ash Runic to create a composite bow with 0 Physical damage, using normal wood (in fact, in only took half the charges to pull it off).