For the most part we have things to make hitters hit harder with weapons, and wearable items to advance the magical skills of wizards. There are even a few items for both areas for the thieves, but nothing I see that is specifically for an adventurer.
The name of the class presumes a person that likes to explore, and to that end, we could revamp the old questing system to be specifically for this type of play and only available to the adventurer's classification. If there is to be true role playing in this game, I would think there would have to be a starting point. Starting adventurer's could have homes that start them at differing beliefs and the associated temples. A return to temple ability, where they could gear up anything needed for their class and advancements in their beliefs, make them able to access specific abilities their belief gains them both in magic and in weapons their Deity allows. It does not need to be large, but something that differentiates them from other classes.
Later in levels these quests may have a need to join forces with those of the thief, wizard and warrior classes to continue, or they may choose a path that allows them to remain solo.