You have spent an extended period of time studying a particular type of weapon that you have now mastered.

Choose a type of weapon(ex. swords, hammers, axes, or bows). Your attack rolls with your chosen weapon score critical hits on 19 and 20 and you have advantage on attack rolls using your chosen weapon.

Additionally, if your chosen weapon type has the ranged property its normal and long ranges both increase by 30ft--OR--You can use the versatile property on your chosen weapon while wielding it in one hand.

Because of this extended study of your chosen weapon, you have lost some of your skill in other weapons. When making attack rolls with any weapon other than your chosen weapon, you roll with disadvantage.