Dangerous is both a Property and Trait.
While under the effects of this Property the following is applied to Dice Pools you generate:
Should you achieve Critical Failure, you suffer additional consequences beyond those normally applied by a Critical Failure.
These consequences will be defined by the Item, Ability, etc conferring this Property.
Example: When rolling an Attack with a Pistol, should you achieve a Critical Failure, it would cause a Weapon Jam meaning the Pistol would immediately lose all of its Ammo. This is in addition to Failing the Attack against the original Entity as normal for a Critical Failure.