Awakened Tempest, +2

To attune to this longsword, you must swear fealty to the Master of Green Blades, as a warlock. You can use the sword as a spellcasting focus for your spells holding it, and you gain a +2 bonus to spell attack rolls and to the saving throw DCs of your warlock spells. Though it is awakened, the final form of this blade is yet to be discovered.

Weave Cut: As an Action, roll 1 warlock hit die, and subtract the rolled number from your maximum HP, forever giving a part of your life up to cast Disjunction - a level 9 spell that removes all magical effects in a wide area, and can disenchant magic items. 

The spell creates a 40-foot radius sphere around a point visible to the caster within 120 ft radius, that causes all magical effects and magic items to become disjoined, excluding artefacts. Doing so causes all spells and magical effects to end, and magical items that fail to resist the spell are stripped of their enchantments and become non-magical. Alternatively, the spell may be directed at a creature or an object if the wielder of the blade successfully hit's the target with a melee attack.

Artifacts may be disjoined, though successfully doing so has a chance to destroy the Tempest entirely.

Weave cut can’t be used again until the next dawn.

 

"Weave is the cycle of creation, violent and beautiful in it's wake. Everything around you is a vortex of the weave. Even time itself. This vortex starts and ends with the tempest."

Proficiency with a Longsword allows you to add your proficiency bonus to the attack roll for any attack you make with it.

Notes: Bonus: Spell Attacks, Bonus: Spell Save DC, Warlock, Versatile, Sap