Probably rank right up there with throwing a pistol at someone after having emptied the clip. A last-ditch effort to be sure.
I always laugh when the guy in the movies does that. They would be better off defending themselves with, as the joke from "Aliens" goes, 'Harsh language'.
A pistol without ammunition is not entirely useless. It makes a fair hammer and decent club and there is always the option of deception and guile. Bluffing during a conflict can be an effective strategy.
In one historic story a US soldier was single-handedly guarding several hundred enemy POWs. After several hours he saw an officer and quietly confided that his rifle was empty and that if the prisoners resisted he would be lucky to defend himself much less keep himself from becoming their prisoner. The officer offered back that his pistol only contained one cartridge and that perhaps it was best if the prisoners didn't know about their predicament.