1. - What if the Warden could reach into small player-sized spaces to catch and/or attack them? They could be led away by other players if they throw a snowball at the Warden, or the target could maybe use an item that emits vibrations for a short amount of time in order for said player to ender-pearl through a small hole between the Warden and the wall. That could support Survival multiplayer and Adventure Map creators.
2. - What if you could wipe the rust off of Copper Blocks to 'weaken' the stone in the deep dark so you can mine them? You could combine the rust with an excavation brush to wipe it on the D.D.stone in order to mine it, but not harvest it, even with silk touch. Or alternatively, you can mine it with silk touch, and using some rust, the D.D.stone, some sculk blocks, and an eye of ender/ender pearl, you can make some kind of fast travel teleporter to prevent the long travels between the player's main base and their deep dark outpost. It would work similarly to how the ender chest breaks, you would only collect the sculk and D.D.stone if broken without silk touch. This would support Speedrunners and Adventure Map creators.
I'm not a big fan of either of these ideas, but I do like the concept of using oxidized metal. Verdigris (the oxidization on copper) is used in dyes, fungicide, and medicine, so perhaps we could see some neat potions made from it as well as new recipes for some existing dyes