I have always found it frustrating that we can't easily see at a glance if the armor type of an item is not our optimal one, (for example, Leather as a Plate wearer), because there's no indicator for it. So I've wrote this minimalistic addon (only 1.9 kb) to attach a single-line warning at the end of the tooltip if the gear is a different armor type from what your class uses.

💠 Usage 💠
* Hover over any gear item in your bags, vendor window, loot, or chat link.
* If the item is not your designated armor type, a single warning line will get attached at the end of the tooltip.
* Cosmetic items (shirts / tabards) are ignored automatically, preventing unnecessary warnings for purely cosmetic items.

💠 Features 💠
Minimal, Lightweight and Efficient
* No unnecessary tooltip:Show() calls; instead, it uses the official built-in tooltip update system.
* Uses GetItemInfoInstant() to efficiently check item data without causing tooltip spam.
* Uses TooltipDataProcessor.AddTooltipPostCall(Enum.TooltipDataType.Item) for modern Retail compatibility.
* Uses the official in-game color handling with RED_FONT_COLOR:WrapTextInColorCode instead of hardcoded hex colors, so it automatically adapts and blends into the UI seamlessly.
Only Processes Visible Tooltips
* No flickering or disappearing lines, even when tooltips are dynamically rebuilt.
* Only checks tooltips that are visible, avoiding unnecessary background processing and Lua errors.
Duplicate Warning Prevention
* Checks if the tooltip already has the warning line.
* Ensures the warning is never added twice, keeping the tooltips clean.

💠 Installation 💠
Copy the folder ArmorTypeWarning into _retail_/Interface/AddOns/.
Enable the "ArmorTypeWarning" in the in-game AddOns window.

💠 Feedback 💠
I only play and test in Retail version, so i have no info about Classic compatibility.
Any bug reports are welcome in the comments section.

Armor Type Warning (Cloth / Leather / Mail / Plate)