Base Class: Rogue
Sellswords, brigands, cut-throats: All names for men who are better at killing for gold than dying for a cause. You are a blade for hire on the battlefield or in back alleys. Mercenaries don't fight for honor, fealty, or homeland, your only concern is getting paid. While you may lack some of the formalized training of more chivalrous men-at-arms, you are more than willing to use every dirty trick in the book to come out alive.
Dirty Fighting
Starting at 3rd level, you take every opportunity to harass or trip up your opponents, you can use the bonus action granted by your Cunning Action to attempt to shove a creature, or to make an improvised weapon attack.
Soldier of Fortune
When you choose this archetype at 3rd level, you gain proficiency in martial weapons, medium armor and shields, and you may make sneak attacks with any simple or martial weapons that don't have the two-handed or heavy property.
In addition, you have advantage on any Charisma check that deals with payment or rewards.
Opportunist
At 9th level, you are expert at exploiting any opening your opponents leave, you have advantage on attacks made on other creature's turns.
Versatile Shield Arm
At 13th level, wielding a shield does not prevent the use of that hand. But you suffer -1 AC while using that hand for something other than supporting the shield.
Swift Revenge
When you reach 17th level, you are able to enact deadly revenge on anyone who attacks you in melee combat. You may make an attack after using Uncanny Dodge against a melee attack.
Just some suggestions for alterations/clarifications since the editing process is somewhat slow:
Soldier of Fortune sneak attack options are in addition to your normal ones, (you can still sneak attack with longbows!)
Swift Revenge is intended to be a melee weapon attack against the target who attacked you.