It is something of a pity that the great Catholic demonologies have somewhat fallen by the wayside. The flip side of hagiographies of the saints, demonologies described the purposes and modus operandi of individual and collective demons.
The utility of both was first, that if a demon or demons were recognized, there was typically an individual saint whose virtue was particularly effective against that or those demons.
For the learned laity, the value was in detecting them, so that they could more accurately describe the pestilence or injury to clergy, helping them to divine possible causes and remedies.
There have been people from a neighboring diocese (another state) come to try to get our diocese to train and install a team of exorcists. As far as I know, it hasn’t happened yet.
Every diocese used to have one.