This has nothing to do with ArmorGrp/WeaponGrp. Every item has a component that appends this info to the item's tooltip if the iteminfo contains a non-negative value on "CurrentDurability" and "Durability" which you send from the server. If the value is 0, the following tooltip won't display.
If you want to remove this for all items, simply hardcode the "durability" or "mana" block in the AbstractItemInfo packet (name would depend on your codebase) to -1, or do it individually per item through its corresponding xml properties. (You don't necessarily need to modify the interface if you just want to remove it)