Officials say the grenade, which landed roughly 30 meters from the podium where Mikheil Saakashvili and George W. Bush were standing, did not go off due to a malfunction.
Jimsheladze said that, if found guilty, her client could be sentenced to up to 15 years in jail.
Arutyunyan was arrested last week in a Tbilisi suburb after killing one policeman in a shootout and receiving several gunshots.
He could face an additional 20 years in jail for the killing of the police officer.
(compiled from local television reports)