You create shimmering arms of force that appear behind you.  These arms can hold weapons or shields and cast spells for you.  While you have these arms, you can take the full attack action and only receive a -3 to each attach, but you must make the attack with a second weapon.  Alternatively, as a full action you can make one attack at a -3 and cast a level 0 spell with any spell requiring an attack roll to be made at a -3.