Things like Pancerz shirt could be renamed to a more fitting thing like Kolczuga Shirt, or Rycerz Armor to Rycerski Armor, but i dont think theres any need for that since both are fully understandable.
Its funny to think of that, since pancerz = armor, so pancerz shirt = armor shirt, if we would swap it to Kolczuga shirt it would mean Chainmail Shirt.
Or, rycerz = knight, rycerz armor = knight armor, rycerski = knightly, so rycerski armor = knightly armor.
I've been using english on a daily basis since i was 8 or 9 so Zimke feel free to ask me if you have any problem with naming Polish based items, ill be glad to provide any help needed.