Mastering swordsmanship and the arcane to boost your abilities you learned spells to enchant your blade and slaughter your enemies. You can cast any spell in your arsenal as a bonus action and give your blade the effect of the spell. You cast the spell as a bonus action then make an attack with your weapon. On a hit the creature receives the effect of the spell

Good with blades and protection

Starting when you choose this subclass at 3rd level, You gain proficiency with Swords and Medium armor

Upper hand in magic and dexterity

At 7th level you gain advantage in spell attacks and dexterity.

Spellcasting

You can cast spells on your blade as a bonus action. And then attack an opponent. If the attack hits the spell takes effect 

Special attack: Atmospheric cutting

At 10th level you learn a special attack called Atmospheric cutting 

Advantage in melee

Geting to at 15th level you have gained advantage on all melee attacks. If you roll 2 nat20 you get to make 2 crit attacks on that turn without the use of action surge

Expert Swordsman with a special attack

At 18th level, you attain the pinnacle of knowledge in swordsmanship. You gain expertise with all swords and you learn a special attack