An Item That Only Builds Into Thornmail To Solve The Cold Steel Issue

Stacking Randuins Omen and Thornmail has a cold steel stack. Should an item be made as the second component for Thornmail, that can only be built into Thornmail, similar to how Lost Chapter literally only serves one purpose. If you can make a Bramble Vest, which only builds into Thornmail, you can make another second item that speaks to the uniqueness of Thornmail like Bramble Vest does. I feel like Wardens Mail was literally picked because it has Mail in its name.