Elemental Executionist

Attaining a sword of elemental power you grow along with it slowly learning the ways of the elements. Using fire, water, lightning, and earth you are able to slash down foes, become more durable to the elements, track them in the wild, overcome enemy's natural resistances to them, and eventually even cast them from your sword to attack from afar. 

Elemental Slice

Once you gain the ability to harness your swords elemental power at 3rd level you can enhance your blade with the power of the elements. When initiative is rolled you must state which kind of element you will be using from fire, water, lightning, or earth. When you hit a creature with your sword you can also deal an additional 1d6 of either fire, cold, lightning, or force damage as a bonus action. Once you become 7th level in this class it becomes 1d8, at 10th level it becomes 1d10, at 15th level it becomes 1d12. You can do this equal to your proficiency bonus. You regain all expended uses after a short or long rest

Elemental Resistance

You have gotten used to your elements surging through you over time. At 7th level at the start of initiative you can gain resistance to the elemental damage type you choose for your Elemental Slice.

Perceive the Elements

Growing more connected with your sword allows your to sense the elements of nature. Due to your link with your sword at 7th level you are able to track any kind of the elements. You always know when it will storm, how to check for all types of water sources, track nearby fires, and gain tremorsense of 20ft. You also gain proficiency in survival checks.

Favored Element

At 10th level you become more in tune with one Element of your choice. Once per short rest when you use your Elemental Slice you can choose to treat resistance to that damage as normal damage and immunity to that damage as resisted. You can change this Element when you gain a level in this class if you so choose. 

Elemental Adaptation

At 15th level you sway your sword to rapidly activate or switch your Elemental Slice damage and resistance. When you are about to take Fire, Cold, Lightning, or Force damage out of combat you can spend a use of your Elemental Slice to take half damage instead. In combat you can switch from your initial Element to a new one spending a use of Elemental Slice as a bonus action. 

Elemental Slash

You have become adept at controlling your battle element. You can now use an action to make a ranged slash attack (30/60) with either strength or dexterity on a hit you do 6d8 of the damage you chose at the beginning of initiative. You can do this once per long rest.