Tonguez
A suffusion of yellow
There are a couple of West African traditions that associate entering an Iron smiths forge with legs getting broken too (Ironwork is often considered super natural).This seems highly speculative. As far as I’m aware, only Hephaestus is a lame smith: Vulcan is a syncretized form with an earlier Etruscan deity, Velchans, about whom little is known. And Volund isn’t attested until the 6th century (and that’s dubious), and may himself be a syncretic deity, incorporating Vulcan.
Which is to say, lameness/deformity is a function of the character of Hephaestus, not of gods of the forge in general. But there might be something I’m missing.
But it could well be that Hephaestus is the origin and that the North Europeans absorbed the tradition via the Romans