So for anyone interested in how I got the vest shiny again...
First, a few caveats... 1) this is something I would suggest only as a last restort, i.e. you accidentally went swimming in your vest, or your mom/wife threw it in the washer/dryer and all the shine came off. Or some other type of appliance tragedy and there is no going back. 2) I'm not sure this would work on fabrics other than the special treated cotton used by clothears and on the original vests. Other types of cotton or synthetic fibers might not like this method at all. 3) Do this at your own risk. It worked for me on my clothears vest and that's all I know. Perhaps this will make the fibers rot in a few months, or maybe the shine will just fade away in a few more weeks. I do not know. However, right now I am quite happy with it. 4) This is really just a short term, quick and cheap solution. A longer term more expensive solution is just to get a new vest.
I tried a bunch of things but the only thing that worked at all was
wax. Gloss sprays and fabric starches just made the fabric stiff and more translucent. Absolutely no good.
I started off with a microcrystalline wax used by museums for securing displays, but it's so viscous that it needed to be heated in order to get it thin enough to apply onto the fabric. It did work in the end but it was extremely difficult to do and I wasn't ready to try it on the whole vest. But then I remembered! A while ago,
bcurtis recommended a specific wax to use to seal the left gauntlet rocket tip copper, and I still had almost a whole tin of it left sitting around, so I thought I'd try that. It has a toxic smell but it's a very low viscosity which means you can just rub it on directly to the fabric without any intermediary steps. Super easy! In the end, that's what worked. My only worry was the smell might be because of some kind of petroleum product that keeps the wax thin, and maybe that might damage the fibers eventually, or make the vest highly flammable

. Who knows. But it is a product used for preserving museum artifacts, so I'm hoping not. As I said, right now it seems to be fine and the smell goes away in 24 hours.
This is the stuff...
You want to put it on real thin. And it will probably take a couple layers before it starts to polish up nice and shiny. You don't want to put it on too thick where you lose the texture of the fabric and it just becomes a sheet of white wax. Just rub it in gently and keep it thin. I used my bare fingers mostly.
close up of the fabric after applying the wax....
This is what I mean about not losing the texture of the fabric. You want to coat the fibers with the thinnest amount possible that will still shine up with some polishing. Polish with something stiff and smooth. I used a piece of plastic the size of a guitar pick, focusing on small sections at a time. If it has gotten too thick in spots you can scrape it down as you buff it.
My gloves had very little shine left, too, so I did those as well...
That's it. Remember... last resort. Ideally you want your stuff to made properly from the start so you do not have to deal with such shenanigans. If my vest spontaneously explodes, or my gloves suddenly powderize themselves, I'll be sure to come back here and revise this post.