Enchanted Gilding

When cast, the metal used for the material component of this spell melts and into a thin layer that covers a weapon or piece of armor the caster is touching, giving it a magical effect depending on the metal used. 

Iron Weapons and armor gain 1+ attack or AC bonus as well gaining advantage when attacking Fey if a weapon or imposing disadvantage against Fey trying to target the wielder if armor.

Gold Weapons and armor gain +2 attack or AC bonus as well as your armor dealing an additional 2d4 radiant damage or your armor granting the wearer resistance to radiant damage.

Silver Weapons and armor gain +2 attack or AC bonus as well as granting advantage against Undead as well as any other creature vulnerable to silver if a weapon or granting the wearer resistance to necrotic damage if armor. 

Electrum Weapons and armor gain +2 attack or AC bonus as well as giving weapons the ability to deal an additional 2d4 lightning damage on a successful hit or if applied to armor grants the user resistance to lightning damage

Platinum Weapons and armor gain +3 attack or AC bonus as well as a +3 bonus to all charisma saves, checks, and spells using the charisma to cast

Mithril Weapons and armor gain +3 attack or AC bonus as well as dealing an additional 2d4 of the weapons damage in darkness if applied to a weapon or give wearer the ability to hide in darkness as a bonus action

Adamantine Weapons and armor gain +3 attack or AC bonus as well as your weapon being able to crit on a 19 or 20 or your negating critical hits