As a bonus action, touch one weapon with a runestone to imbue it with the corresponding element. On a hit, the target suffers the weapon attack’s normal damage and 1d4 fire damage. Additionally, the elemental damage dealt by this enchantment is considered magical for the purpose of overcoming resistances.

At Higher Levels. When you cast this spell using a spell slot of 3rd level or higher, the damage increases by 1d4 for every two slot levels above 1st. Additionally, using a spell slot of 3rd level or higher grants a duration that doesn't require concentration.