Sword beam attacks in MF.

[Agrippa]

There's a convention in pop culture, and Celtic Mythology, called the sword beam. Basically a melee weapon that can launch a bolt or wave of energy as a ranged attack. It would most likely draw power from an energy pack, the wielder's own life or magical/psychic power or ambient energy. so my question is, how would you stat up a melee weapon with a beam attack?