Stormreaver is a masterwork falchion, but acts as a magic weapon for the purposes of overcoming damage reduction.  You can use the Weapon Finesse feat to apply your Dexterity modifier instead of your Strength modifier to attack rolls with Stormreaver, even though it isn't a light weapon.  You cannot use the Power Attack feat when weilding Stormreaver in this fashion.

Stormreaver has three charges, which are renewed at dawn each day.  Spending 1 or more charges creates an effect as described below.  The sword's owner must have a racial connection to the elemental plane of Air in order to use Stormreaver's activated abilities.

1 charge: As a swift action, Stormreaver's critical chance increases to 15-20 for the rest of the round.

2 charges: As a standard action, Stormreaver emits a flash of light that blinds all other creatures within 20 feet of you for 1 round (Reflex DC 10+½ level+Wis modifier negates).

3 charges: As a standard action, you point Stormreaver at a target and transform into a bolt of lightning, dealing 1d6 points of electricity damage/level to each creature in a line beginning at your position (Reflex DC 10+½ level+Wis modifier for half).  You can travel up to 10 feet/level, and you immediately reform at the end of the path.  You set fire to combustibles and damage objects in your path. You can melt metals with a low melting point, such as lead, gold, copper, silver, or bronze. If the damage caused to an interposing barrier shatters or breaks through it, you may continue beyond the barrier if your range permits; otherwise, you stop at the barrier.  You are shaken (-2 penalty on atttack rolls, saving throws, skill checks, and ability checks) for 1 round immediately after using this ability.

Stormreaver is a dark, murky gray falchion that has passed through the hands of Air Genasi warriors for centuries.  It draws from the soul of the wielder to fuel its power; only those with a strong connection to the element of Air are able to unlock its abilities.