Playing Pathfinder: Kingmaker has reminded me of some elements of D&D. One of these elements are metals.
Cold Iron doesn't exist in Felltower. In the game, it seems to largely serve to injury faerie-type creatures. It was a metal type that got some random mentions in AD&D, too, that I recall, but it wasn't very defined.
Felltower features the usual DF metals:
It also features, although not commonly, bronze weapons and armor as well.
Orichalcum is in short supply - the PCs bought up some items made of it, mostly knives (which are still affordable even with a +29 CF.) Its main value is that it won't break on a parry. The PCs haven't knowingly met anything especially vulnerable to this metal type; it's not clear why anything would be.
Meteoric isn't uncommon, but is sufficient rare to be cheap and always require a special order. Its main use is to frustrate defensive magic. The PCs haven't knowingly encountered anything especially vulnerable to this metal type; presumably beings with some kind of sensitivity to a lack of magic could be affected more than usual by it, but cases are likely to be extremely rare.
Straight-up steel is the main metal. It's common, and almost nothing takes extra damage from steel.
Silver is excellent against were-creatures and presumably some other beings as well. In general, if it shifts shapes, silver might help.
Bronze is uncommon because working with it is a speciality task. It is useful against rust monsters (for sure) and rust slimes (presumably), but suffers against steel and orichalcum.
That's about it for metals for weaponry. "Cold forged" weapons or "iron" weapons aren't getting you much of anything. A being vulnerable to "iron" is just as vulnerable to steel.
Felltower is pretty much vanilla DF in that regard.