While a lot of you folks are suggesting for wireless wiring mechanics, I have an idea about a tool; a flat screen that pretty much allows you to manipulate (like activate or rearrange active connections) wireless connections through an interface that borrows some features from the newly-implemented camera mode. To use the panel, one would need CCTV-like cameras that reveal an area around to where the camera is placed. When you are viewing on camera, there'll be two modes you can select in which you are to activate or rearrange connections within the said area. To balance out a few things, the camera and the panel will be using a fairly large AOE.
That being said, it would be a step forward towards the security systems players implement when defending their own towns against in-game events like hardmode bosses, solar eclipses and the like.
As for other stuff, I would like to see a hardmode version of Arkhalis; a sword that's slower than the pre-hardmode Arkhalis but has a larger range, and more DPS. To fit the Castlevania theme/reference, it would be droped off by a Giant Cursed Skull. Oh, I also have an idea for a unique drops from the celestial towers: Diana's sword from LoL that allows you to dash and pass through an enemy, damaging them in the process. To fit with the magical theme of the Nebula pillar, it would be the only sword that deals magic damage so Godly would be the best modifier. Then a gauss rifle or a rail gun from the vortex pillar that uses a fair amount of mana for its high base damage and penetration. Next would be Leona's sword from LoL
that dropped by the solar pillar. It doesn't have any other effects but a unique flame debuff. For the stardust tower, I would like a staff that allows you to summon a stardust soldier that attacks enemies with a spear. The soldier functions like a turret so if you want to reposition him just left click on the next place where you want him to be. Kind of similar to Azir's sand soldiers, right?
For other stuff, I kind of want unique purchasable weapons from the mechanic like the Crowbar and a unique wrench that isn't used for wiring, but mauling slimes up.
Also, I kind of want to see a hardmode magical bow that uses mana instead of arrows that drops from Plantera.
NOTE: the devs probably forgot to add Aaron's wings on the 1.3 update.