So the description of a Finesse weapon is that when you make an attack roll and a damage roll, you use either Strength or Dexterity, and it must be the same stat for both rolls. However, Hex Warrior says that, as a warlock, you can use your Charisma as an attack modifier.
Now, since the finesse weapon description states that both rolls must be the same, and Hex Warrior modifies it to Charisma, does that mean that the damage roll also uses Charisma modifier, since they have to be the same?
The Hex Warrior feature states the following:
When you attack with that weapon, you can use your Charisma modifier, instead of Strength or Dexterity, for the attack and damage rolls.
This rule applies whether or not the weapon has the finesse property.
The word "can" means using this feature is optional. For example, if the warlock's Strength modifier is greater than their Charisma modifier, then they can still use their Strength modifier for the attack and damage rolls.
Note that if the warlock makes an attack that wouldn't add any ability modifier to the damage roll, they would not include their Charisma modifier in the damage calculations. For example, if the warlock is using two-weapon fighting and makes an offhand attack with this weapon, then by default they would not add any ability modifier to the damage roll.
