Metal objects are notoriously difficult to add runes to. Given forged metal's relative purity and uniformity compared to natural objects, it is nearly impossible to tap into any properties of the material that are not already manifested.
The 'inlay runes' skill allows druids to add runes to metal objects. It relies on sympathetic magics that arise due to interactions between two different types of metal.
Once an item is inlaid with a rune composed of one kind of metal, all subsequent runes must be of the same metal.
The process requires a ductile metal and a forge. Like all forge services, it has a gold cost. It is not nearly as expensive as rune-based enchantments, but, like all rune-carving, it is not as potent. Harder to work with metals cost more to inlay, but improve the chance of success.
