He has a proficiency with a rapier that doesn't come from his race or class.
He's called the Blade.
We meet him while he's training sword fighting techniques.
The "just a title" angle doesn't feel good to me.
Obviously, so many folks think his character would function better as a Hexblade for a reason. It just makes sense. Or at least him having the pact of the blade, which explains his odd proficiency. Now it's just a question of beefing up what Pact of the Blade means in BG3, because what it means in 5e probably doesn't translate that well into the game.
