Be careful though, it turns the weapon itself into an iron rune… meaning it works even if the weapon is unequipped or unusable. So if you give it to an iron sword, everyone can slap those in their inventories and have the iron rune effect with any other weapon.
I specifically requested that someone make an iron rune effect just for equipped weapons in combat a year or two ago… it’s probably lying around somewhere?
Edit: LMAO Tequila, YOU coded it! [FE8] Iron Rune effect on weapon: Only when equipped