Black Stone (Armor) and Hard Black Crystal Shards are still dropping as loot from mobs. Confirmed in Ash Forrest and Gyfin UG and likely other places as well. They are also still coming from "Enhancement Help Kit", such as the ones you get from exchanging Plump Coelacanths.

* These need to be removed from loot tables (and likely increase drop rate of Black Stone (Weapon), and Sharps to compensate)

* The Enhancement Help Kits need to be updated to drop more of the weapon stones and sharps and have these removed.

Update: The Hard Black Crystal Shards are also still dropping from Oasis Box of Secrets that is received from Twitch watch rewards, as well as the Black Spirit's Adventure Boxes from the BS Adventure dice game.

I think they will still be in the loot table for a while, but they will no longer be usable. You can exchange them with the black spirit though.

Right, this is being done in phases.