The Line
the anvil-singers and the erudite runecasters, crossed
The Recipe
Inputs: Steel or Mithril, a spell's Exchange (spent into the object), the runecaster's rune Output: a blade that holds a promise — an enchanted item Time: a year for the blade, a season for the rune, and the Exchange is the cost
The enchanted blade is the crossing of the two systems: the spell's Exchange is spent into the object instead of into a reagent, and the object is the one who holds the promise. It is why enchantments are rare — the maker has to know both legs of the table — and why they can be broken: the promise can be unkept, and the unkept is the wild spell.
The recipe is the knowledge, and the knowledge is the one the guild charges for — on the ladder in The Maker's Hand, the recipe is the middle leg: the world gives the material, the maker knows the recipe, and the item is what the maker owes.