Executioner

It is the executioner's duty to kill those around them in the most efficient way possible. Those who practice this art trained their entire lives. But, an executioner's life is surrounded by death and is one of the most gruesome jobs one could do. Those who take this path tread with death.

Death Sense.

Starting at third level, you understand everything behind death. You gain expertise in the medicine skill, doubling proficiency in anything at all. Additionally, once per day, you can sense how close someone is to death.  This increases at the fifth, eleventh, and twentieth level.

Armor Weakness

At the seventh level, you can spot the kinks of an armor. The ability changes depending on the type of armor that the enemy wears. This is considered an action and you can't do any attacks.

Natural: You crush or break the scales of a creature at a certain point. Any time you attack the creature again, they have to subtract their total AC by 2. Anytime they are healed, the feature is considered null and void.

Light:  You aim for the vital point of the armor adding a 1d6 times two to your damage if you hit them. This damage increases by 1d6 every four levels.

Medium: You hit the armor with the flat of the weapon, subtracting two from there AC after denting it while also taking your weapons attack times two. The damage is considered force damage. 

Heavy:  You strike with a disadvantage at a certain area of the armor. If it hits, you break the armor giving them a disadvantage on any attack checks for four turns. After that they get used to it and attack as norma;

Death Spin.

At the tenth level, you learn how to better deal death to those all around you. As an action twice per day you can you this ability to attack all of those around you in a three by three square. Each of the creatures hit is moved back ten feet, knocked back after a strength check. They also take double the damage that you roll.

Deft Swing

A fifteenth level you strike with overwhelming force. You do a straight roll to see if you hit the enemy. If you hit the enemy they take 3d your weapon damage. If it's a greatsword it's instead 6d6. This action costs two attacks to use.

Execution

At the 18th level, you have mastered the art of beheading. Whenever an enemy is knocked prone or is unsuspecting of the strike, you hit the creature with advantage and deal you weapon damage time ten. The strike lacks eloquence and skill but it doesn't matter if you can kill the enemy with one strike.