To cast magic in The Citadel without any Casting (Citadel) rituals or spell components (such as Harmony and Focus)-- but rather by will alone is called Raw Casting. This increases the risk of Tearing exponentially.
Raw Casting is akin to a parent seeing their child under a car, and lifting the car. Sometimes, it makes for some real, fantastic wondrous spellcasting that no one thought possible of a simple baker - but... more often than not, it also ends in the caster Tearing or somehow hurting themselves, be it mentally scarring or physical such. Raw Casting is just as bad as lifting a car is; your muscles won't like you, and you might just drop the car on yourself. It's a knee-jerk reaction, and outside of your control.
Hurting other people, even in self defense, is tricky - even though the people of The Citadel are Magi, at the end of the day they are just ordinary people and will not reach for a spell unless it is a last resort. A baker will reach for the nearest knife in their kitchen, for example.