Battlemage's Edge

One melee weapon you are holding becomes imbibed with intangible energy, channeling the essence of War Magic into the Battlemage's Edge. You can use your spellcasting ability instead of Strength or Dexterity for the attack bonus and damage rolls with the Battlemage's Edge.
When wielding the Battlemage's Edge, you gain the ability to use the weapon's magic to counter attacks and store their energy. Whenever you're forced to make a saving throw or an attack roll is made against you, you can use your reaction to give yourself a bonus to your AC or the saving throw equal to half your proficiency bonus, rounded down. Whenever you use your reaction in this way, you gain one energy charge.
Once on your turn when you hit a creature with the Battlemage's Edge, you can expend one energy charge to create one of the following effects:

• The creature takes an additional 2d6 force damage.
• The creature must make a Strength saving throw or be pushed 20 feet away from you, landing prone.
• A magical ward of energy surrounds the creature, giving it disadvantage on attack rolls or saving throws until the end of your next turn.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the bonus increases by +1 for every two slot levels above 3rd.
Classes: Paladin, Warlock, Wizard
Subclasses: Valor Bard, War Cleric

3rd level transmutation
Casting Time: 1 bonus action
Range: Touch
Components: V, M (one melee weapon you are holding)
Duration: Concentration, up to 1 minute