Custom elf subrace abilities?

[Totema]

In my homebrew 5e campaign setting, there's a fourth subrace of elf that's meant to compliment the high and wood elves. In-setting, they are described as being very high-cultured and open-minded, and would rather parley with a potential enemy than jump into a fight blindly. Mechanically, I'm giving them their +1 to charisma as well as the same elf weapon training as the high and wood elves, but I'm not really sure what else to do with them. Come to think of it, I'm actually not sure I want to keep that same set of weapon proficiencies, but I'm keeping them for now unless I can come up with something to offset the need for them. Anyone have any suggestions?

[Dyhmas]

Well, if they are a diplomancer subrace, proficiency in Persuasion seem to be a must.

-Dyhmas

[Totema]

It does seem obvious but it also seems too little to be an ability on its own. Maybe also add on a special function for persuasion that only they can use, like how rock gnomes get their tinker ability?

[Totema]

Little bump, and also an update to mention I'm looking through my 3.5 material for inspiration for a diplomancer ability. I'm considering something like one of the functions of the 3.5 Master Manipulator feat. I also think getting the Inspiring Leader feat for free might be a worthy alternative, but I'll make the call on that when I'm done looking.

[Totema]

Ok, I'm leaning now towards something similar to the Soothing Voice racial substitution level ability for half-elf bards in 3.5. However it's hard not making it overly complex, especially considering that 5e is supposed to be comparably rules-light. How does this look?

- Elven Politesse. You have proficiency with the Persuasion skill. You can use an action to attempt to soothe the emotions of one creature within 30' that can see and hear you. You make a Persuasion check, and your target must make an opposing Insight check. If you pass, the target is affected by one of the effects of the Calm Emotions spell for 20 seconds, which you decide upon passing the check. The duration increases to 30 seconds at 6th level, 40 seconds at 11th level, and 50 seconds at 16th level. When you use your elven politesse, you can't use it again until you complete a short or long rest.