Only when I chanced on this /r/LifeProTips post, did I know
Most airplane aisle seats have a small lever or button on the underside of the armrest, near the hinge. Pushing or sliding this lever will release the hinge lock, allowing you to raise the armrest.
When horizontal and down, aisle armrests obviously hinders exit during emergencies when saving seconds can save lives, especially for more obese passengers. So why isn't this hidden button/lever disclosed to passengers, like in the mandatory safety briefing or video?
I'm not asking about armrests between seats that don't require a hidden switch to lift.