Sockets/Runes mechanic needs an addition.

The sockets and runes mechanic is a good way to add that extra resistance you may need to cap your resistance as we no longer have a crafting bench or any other crafting mechanic from poe1 that could help you enable an item to be an upgrade to your build.

An issue with the socket and rune mechanic right now though is that it's a one time use per item which really limits or locks you from further gear progression.
As an example, you may find a pair of boots that would be an upgrade as it may have more movement speed, more life etc. compared to your current boots and you'de love to use them. but then you realise your current boots have cold res and the new ones have lightning res and you're in trouble. replacing them would make you uncapped in cold res and overcaped in lightning res and adding a socket to the new boots to get some extra cold res from a rune may still leave you uncapped on cold res. Now in order to enable this gear upgrade you have to replace another piece of your gear to fix your resistances. Early into the game this is no problem but the further you progress on better gear the more this becomes a problem.

Another example is you may find another player selling an item that would be really good for you but the previous owner already used the socket on the item and that socket is useless to you so now you have a useless rune if you decide to buy that item and this would limit you even more down the line replacing other gear pieces as you effectively would have one less socket to play around with.

Solution: Add a new Orb or something to the game that removes sockets from an item so that we can reapply Artificer's and add a different rune. At first I was thinking Artificer's Orb could either add or remove a socket but as some items can have more than one socket that would be a problem so a new Orb or something would be necessary.

With no deterministic crafting in the game at least let us play with the runes to solve that last missing piece of the puzzle. Game is already rng enough when it comes to gear.

Just make replacing the rune destroy the old one. Boom.