Armor (chain shirt), uncommon
Mithral is a light, flexible metal. A mithral chain shirt can be worn under normal clothes. If the armor normally imposes disadvantage on Dexterity (Stealth) checks or has a Strength requirement, the mithral version of the armor doesn't.
Made of interlocking metal rings, a chain shirt is worn between layers of clothing or leather. This armor offers modest protection to the wearer's upper body and allows the sound of the rings rubbing against one another to be muffled by outer layers.
Notes: Stealth Disadvantage: Remove, Combat, Warding
I noticed that if I equip my chain mail and my mithril chain shirt it gives me the armor bonus of the heavy armor but negates the disadvantage on stealth checks. This makes sense to me because maybe it replaces some of the chain with mithril but I can’t find anything in the rules that would make this ok. Is this a glitch?
Mithral negates the disadvantage on stealth checks
Equipping two sets of armor is already outside the rules as written. Equip Mithral Chain Mail if you want to do it by the book.