It works. I actually did it by accident. A couple of weeks ago, I got the offering, but didn't get around to turning it in, probably because I just wasn't in the city much at the time. Then, early last week, I did turn it in. At some point later I noticed the offering in my inventory, and I thought that seemed odd, but I didn't realize it was an exploitable glitch at the time. I just thought maybe I'd acquired another one and hadn't noticed.

But, yesterday I happened to watch this video and realized I'd already taken the first step that he mentions. I tried turning it in again, and it worked. There didn't seem to be any limit to how many times I could do it. As the guy mentions, it's not powerful gear, so it won't help increase your maximum light, although I was able to infuse a couple of old Reverie Dawn pieces to get them higher than they had been.

I'm not sure whether it lasts for multiple weeks. I'm guessing yes, but I'll have to check today and see whether it's still there.