For my fury warrior bis recommendations it list Skilled Fighting Blade for both mainhand and offhand. I looked up this item and it is a quest reward, and alliance only. I am an orc. I do not think there is even a way of getting 2 of those.
We didn’t add source information for every single item, so some lower quality stuff might not have faction/quest restrictions on it. We can try to add more of that information. For now you can simply exclude that item.