Eldritch Blade

A length of crackling energy forms around your blade. Make a melee spell attack against the target. On a hit, the target takes 1d10 force damage in addition to the damage of the weapon.

The spell has different effects when you reach higher levels: 

At 5th level you can conjure small melee weapons i.e.: a dagger or sickle. You can also convert small weapons into their large counterparts by covering them in energy i.e. dagger - shortsword/longsword, sickle - scythe. Conjured small melee weapons deal 1d10 +4 force damage. Small weapons that have been converted to their large counterparts deal 2d10 in addition to the damage of the small weapon.

At 11th level you can conjure one large melee weapon or two small melee weapons. Conjured large melee weapons deal 3d10 +4 force damage. Conjured small weapons now deal 2d10 +1 force damage

 at 17th level you can imbue one weapon permanently with the power of the eldritch. You cannot cast eldritch blade on a weapon imbued with this power. If the weapon is destroyed its energy will return to you allowing you to create another. Weapons imbued with this power deal an additional 3d10 force damage. Conjured large weapons now deal 4d10 +5 force damage

Two handed weapons conjured by this spell are weightless and become versatile