Meet Quartz Glow :3
 
A former member of the Crystal Palace police turned bodyguard for hire. She lost her eye during a fight when she was in the Guard, where during a gang fight, one of the ponies she was fighting pulled out a knife and stabbed her in the eye, causing her to lose it.
 
She was a highly skilled officer, often being in the top percentages of various tests and activities. These skills made her highly sought after when she became a body guard, as she is often employed by very popular and wealthy figures (celebrities, business ponies, politicians, etc.)
 
Despite her appearance and how she often seems to act cold and stoic, this is actually just an act she puts on for her job. Outside of it, she is quite kind and jovial, and is a nice girl to a lot of ponies.  
When she is not on bodyguard duty, she works down at a local gym/training area, and teaches martial arts and self-defence/hoof-to-hoof combat to other ponies, based off the martial arts she learned as a police officer.