I think perhaps that the use of the word "devices" should be considered. It doesn't necessarily mean a gadget or a weapon; it can mean a technique, means, or even a plan. As Saruman had most thoroughly studied the arts of the Enemy (possibly even having a sort of inside track on things because of their mutual origin as Maiar of Aule), the Council may have deferred to his wisdom in such matters and implemented his plan for a confrontation with "the Necromancer." It may or may not have included such things as his "blasting fire" (I tend to think that if it did, it was used minimally, since Dol Guldur does not appear to have suffered significant physical damage from the attack). If they came at Sauron with enough non-physical power to make him fear that they might actually succeed in overwhelming him and taking him prisoner, I doubt he'd have much compunction about deserting his minions and hieing himself back to the safety of his much greater stronghold in Mordor.
Just an early morning thought. Still haven't gotten to the books....
