I believe that, for simple enchantments, the smith knows a spell (or an affinity or a feat) to make the weapon sharper or shield stronger or whatever. I suggest that these are limited to a +1 or maybe a +2 benefit.
However, for stronger enchantments, a heroquest is required to invite (or bind) a spirit, soul or essence to inhabit the item. This heroquest could be a ritual, a this world quest or a true otherworld quest and could involve one or more other magicians to find, negotiate/capture and finally bind the entity into the item. Otherwise this is much the same as you suggest but with a slight different flavour: the special components are required to make a fitting home (or prison) for the entity that inhabits the item.
I've always felt that smithing is a very knowledge based skill and that is why I suggest that spells are more likely than affinities/feats or spirits/charms. However, Gustbran is in a theistic pantheon. But there are exceptions like Kolat and, to a lesser extent, Lankhor Mhy in that pantheon.
Powered by hypermail