I just read about this but there's no info on UESP about it other than it's found on a Falmer in Silent City Catacombs, a ruin within the ruin of Blackreach. Anyone know what it does?

The keys are used to open the chests found in Falmer dungeons. No need for lockpicks.

Cool. Not a huge thing, but convenient. Next time I'm in Blackreach I'll pick it up. Thanks.

I'm not sure that is actually the case. I've gotten the Shaman key many times and never noticed it opening anything - or, at least,
I've never gotten a notification that such-and-such was opened using the key, as you normally get from other keys (most often when
I'm looking for the last few locks needed to max out my lockpicking skill). I think the keys were intended for something else that got
dropped and were just forgotten when it came time to clean up stuff like that.

It seemed to open caae, but post one of the patches, it doesn't seem to do anything.

Err nothing special for me as I got I unbreakable perk - lockpicks can't break, so I have an access to everything!