Looks like a well crafted elven bow. In the hands on a non-mage the bow acts as a nornal long bow with a magical +1 to accuracy.
In the hands of a mage it becomes a focus for arcane blast. As the mage pulls the string back they can simultaneous cast arcane blast. A arrow formed of pure magic will appear.
Firing the bow draws 5 magic from the mage. The arcane blast gains the range of the bow and doubles willpower for purposes of damage. Spell stunts apply.