Outlaw Rogue is the pinnacle of Pirate/smuggler and leather has all the good transmogs for it.
Arms/Fury Warrior could fit a Mercenary role.
You could play a Monk with a pirate/smuggler mog and punch things to death with pirate weapons on your back though.
Warlock for mercenary maybe?
I don’t see any other class being able to portray what you’re looking for though.