For me,
An Adventurer is the one who rely on Strength facing all the dangers. Good in Combat, also have good Personality to win the crowd.
An Adventurer must know how to fight, must familiar with a type of weapon. Blade is a typical weapon for any adventurers in fairy tales.
What good a sword fighter if don't know how to Block enemy attacks?
An Adventurer bravely facing dangers, so he/she need an armor, either Heavy Armor or Light Armor.
Being a lone fighter, an Adventurer must maintain own equipment, even he/she may not be a very good Armorer, at least he/she can keep his/her weapon sharp and armor in good condition
Adventurers mostly like to boast their stories to audience, telling how they defeat certain monsters, how they escape dangers, how they found treasures. They also good at finding information, asking about rumors, where they can find treasures or monsters, so they are good at Speechcraft
What their thropies are for? Decoration? Sure no. An Adventurer will sell their treasures, they don't keep it for themselves, because they like adventuring and exploring. They rarely be at home. To get the best price for their treasure from merchants, an Adventurer must be good at Merchantile
Edit : As alternative to Merchantile, an Adventurer sure know how to open locked chests, what good an Adventurer who find locked chest but don't know how to open it? So an Adventurer should know Security
Having a dangerous hobby, it is a good idea for an Adventurer to know a bit about healing magic, how to heal self from injuries, poisons and diseases. Restoration magic is vital for any adventurer.
So there you got my 7 Major Skills, Attributes and Specialization for an Adventurer