EfUSS: Secondary Armor Proficiency.
-3 points: Can wear and remove Light Armor instantly. Otherwise requires 1 round.
-6 points: Can wear and remove Medium Armor instantly. Otherwise requires 5 rounds.
-10 points: Can wear and remove Heavy Armor in 1 round. Otherwise requires 2 turns.
If this is being considered, I would suggest using discipline instead.
Mostly because there's already climb, swim, (Which are penalized by using heavy armor) and crafting efuss skills, and if players needed use efuss points to have their fighter avoid waiting 10 minutes because they found some decent armor, or have something cool like woodcutting in their background, it would be really meh.