Common problem in MMOs. Common problem in real life. It's unfortunate but you can't have people hold your hand through this stuff even if you think it's unfair. If he got the shield, he can do what he wants with it and he is not obligated to give it to you.

Furthermore, that shield is ridiculously easy to get. They're always being sold and they pop up in faction leves pretty much every single time I check them. Don't get too bummed out by it, you'll get one soon enough.