Eldritch Sling

Mastery in casting and an affinity for larger weapons, you can now use your patron's abilities in the midst of combat.

When using a weapon with two hands, you can cast Eldritch blast as a bonus action, using the momentum of the weapon to preform the Somatic part of the spell. The spell only launches one bolt, and will only be affected by any invocations adding damage to the bolt.  The effect is only enables when using two handed weapons.