Crescent of Jannath

The Crescent of Jannath, so named by its Netherese discoverers, is actually an ancient elven artifact of unknown origin. It's true name is not known, nor who wielded it, only that it was found by an apprentice of Arcanist Sargauth around -900 DR.

It appears similar to a large scimitar or falchion, made out of mithral--an alloy of bronze and pure mithril--which gives it a distinctive blue-green mottle atop a silvery sheen. Like all mithral items, it is lighter than it would be if it were crafted of steel, but it is still quite large--seemingly oversized for a humanoid to wield--and therefore requires nontrivial strength to wield effectively.

Statistics

Base Weapon	One-handed, 1d8 slashing damage, 19-20 critical range
Craftsmanship	Fine (+1 to hit and damage, +1 enhancement slot)
Material	Mithral (increases critical range to 18-20, on crit gain a bonus attack)
Enhancement slots	2 (not yet filled)
Special powers	See below

The crescent appears to be attuned to primal forces, primarily the power of Wind, and secondarily of Life. When it is used, it slowly builds attunement to those forces, and grants the wielder benefits.

Special Powers

Wind Power	Each time you spend an action to attack with the Crescent, you gain 1 charge of Wind Power. These charges decay at a rate of 1 per 10 minutes not in combat, and can be spent to power other abilities. Your Wind Power maxes out at 3.
Wind Rush	Costs 1 Wind Power, single action; you rush forward in a straight line between 10 and 50 ft long, slashing at any enemies in your path. Roll a single attack and damage roll; it applies to all targets in the path. The weapon has a reach of 5 ft, so you can strike all targets in the squares you move through, and those within 5 ft (1 square) of your movement path.
Windwield	Whenever you have 1 or more Wind Power, you may throw the crescent as a ranged weapon, rolling the same attack and damage as normal, but attacking at a range of up to 10 ft per Wind Power. Does not expend Wind Power when used.
Cyclone	Costs 2 Wind Power, bonus action; target within 120 ft is caught in a cyclone, unable to take any actions, but also unable to be harmed. Lasts up to 3 rounds, or until you end it. No saving throw is allowed. Subject must be Large or smaller (although if you spend 3 WP instead of 2, subject can be Huge).
Rejuvenation	Whenever you have 2 or more Wind Power when a turn starts, you regain 1d10 + Con modifier hit points.
Steel Tornado	Costs 3 Wind Power, single action; you become a living cyclone, a 15-ft diameter cyclone 50 ft tall, that can move up to 50 ft, ignoring creatures and obstacles other than stationary ones larger than you. Any creature or object you touch in that movement is picked up by the cyclone and tossed in a random direction, suffering first double your normal weapon damage (no attack roll needed), then 5d6 falling damage when they inevitably slam into the ground or a wall after being ejected.
Bramblestrike	Whenever you have 3 or more Wind Power and you land a melee or Windwield attack with the Crescent, in addition to any damage you inflict, you also cause vines and brambles to sprout up from the ground and pin the subject in place (they become restrained, Strength save ends).