Shards awarded for completing fieldcraft leves have been increased.

what leves award shards? only item i have ever gotten from any fieldcraft leve is a Cordial.
I don't know that this is involved in all the leves but I know when I did Alchemist, there were a few of the earlier leves that gave me some Water Shards. Didn't see it much on the upper level leves, but it would give like 5 at a time I think, so they are probably bringing that yield up to be more beneficial to a crafting class.
When gathering, players may now discover items with the following properties:
Rare: Only one of these items can be obtained from this gathering point.
Hidden: This item cannot normally be obtained from this gathering point.
when or how exactly can a hidden item be obtained?
We don't know much about the treasure hunts other than what was revealed in the patch notes, so it's hard to say. The hidden I assume is going to work like the unspoiled nodes in a sense, that you will need a special skill, or perhaps a minimum Gathering/Perception to even find them. More likely though it's just an RNG kind of thing (Random Number Generation) where it's something like 1/1000 probability of finding the hidden... You just never know with SE, if something is valuble, you can bet that you'll either be working your @$$ of to get it, or that it's going to be nearly impossible to find.