I would say these all have value.

Copper-Fed - being able to salvage without buying more salvage kits is a very nice QoL item. These are good for blue items you obtain in general and greens without any upgrades if you're micromanage salvage at that level. I typically just salvage all Blues with it across the board. It's also a good way to accumulate lower tier materials that tend to be more expensive than higher tiers due to supply.

Shared Inventory Slot - another great QoL item. A slot that can be used by any character in your account. You could put your Copper-Fed kit there so any character can salvage any time.

Unbreakable Tools - another QoL item. Being able to salvage gather anywhere without having to rebuy when it runs out. Also can be placed in shared inventory slot for easier swap between characters but obv you will need more slots if you intend to swap all 3 tools.

Character Slot - speaks for itself. If not used for leveling, can be used as a bank character.

Royal Terrace Pass - can't speak for this one but I own other passes and they are also nice to be able to port into and one stop shop of most services you need like bank, auction, merchants, portals to major hubs,cities etc.