For the past three weeks, I've been dragging my stuff from my inventory to the store's inventory to sell it. I thought to myself this evening "Do you know what would be really cool? If they added a feature where you could press Ctrl while clicking on it to automatically sell it." Then I thought "Hmm... maybe its already in." So I tried it and it worked. Makes selling your excess inventory a little easier.
The description does include that message; I see it now that you point it out. Could you incorporate it into the price pop-up instead of part of the description? Instead of it saying "Sell for: 100 Gold" could it say "Ctrl + click to sell for: 100 Gold"? With so much going on visually, I think it is pretty easy to miss the "Ctrl+click:Sell" since we might not expect the description to be location dependent. Plus the italics almost make it less likely to be seen especially if the red text "This item is not usable by this class" is there to draw your eye along with the pop-up gold amount. Or perhaps I'm alone in not seeing it. It certainly wouldn't be the first time I've missed something everyone else sees.
I actually do think most people catch this one where it is... fwiw, in shops you can also buy by Ctrl+click and from your keep you can remove items from your active build with Ctrl+click.