The Use of Magic
All magic using PC's should bear in mind that society has no love for Mages and Wizards. The only way that magic survives is by secrecy, which is imposed by the sects through close vetting of all trainees. All mage PCs will have been through this vetting procedure before beginning their initial training, and are assumed to have passed. They should not use their powers before an unsuspecting crowd, or even before a single peasant, as there are harsh penalties for the use of magic, and witnesses can leave the character in an awkward position.
Even the Magic sects working for the cause of Evil or Chaos are careful of who they allow to view their spells, as one of the collective aims of all sects is to further the acceptance of magic amongst the peasantry; if a report of the use of magic that went wrong is heard it will hardly further this aim. Of course, for evil sects they are less concerned about any peasant who witnessed a spell being cast or a magic effect if they did not survive to report it.
Clerical magic is perceived differently by the ordinary people. The role of the cleric has traditionally been the support and protection of the peasantry, and so most peasants easily accept the powers wielded by clerics; most of what they see is used to healing and strengthening people anyway. Their faith in the gods is furthered by this acceptance; it is a direct benefit of worship, and a testament to the power of their cults. Some clerical spells, however, particularly those of the Elemental and Summoning Spheres, and some from the Combat Sphere, could easily be mistaken for Magic, and have been known to cause panic; the peasants seldom consult the church for guidance before an offender is burned, hanged, or drowned for witchcraft to see if a particular effect really was a miracle of the gods, or just Magic.
Things are different among the ruling classes, however. Magic has become somewhat accepted recently, and almost popular. To those with formal education, it is easy to demonstrate the usefulness of magic; and in general most Lords and rulers are quite happy to keep this power away from the masses. This is a feudal society, and if the peasants could cast fireballs, there would be fewer Lords around to rule. Even among the feudal lords, though, exposure to big magic is extremely rare; the ones that have seem magic being cast have seldom seem more than Melfs Acid Arrow, and may well be shocked and frightened by a missile storm or an ice storm.
As a general guideline, magic using and Cleric PCs should not use spells with a visual effect in villages, towns, and cities where peasants (the lowest classes) are around. In the presence of Artisans, Craftsmen and Business folk (the middle classes) it may be possible to use minor, information gathering spells, such as Identify. Where the upper classes are concerned, most low level spells are probably acceptable (although their guards are at best from the middle classes, so take care).