Feats of Daring: Purple Dragon Feat for D&D 5th Edition

What I'm working on is inspired by 3E's Regional Feats for the Forgotten Realms and Fighter Kits from Warriors and Priests of the Realms and is currently designed for fighters:

Purple Dragon Feat

Prerequisite: Fighter

• You are schooled in etiquette and may add your proficiency bonus to any ability checks related to socials customs.

•  You are proficient in vehicles (land) and own a light warhorse.

• You gain a +1 bonus to Strength and Constitution saving throws.