The concept of Sect comes to us from Hellenistic times. It is a concept that fell out of use for many years, but is being rediscovered as more and more astrologers are re-examining ancient techniques. Sect can help you determine the the qualities of a planet, whether for good or ill, and its effect in the chart.
Depending on whether it is a daytime or nighttime chart, sect tells you which of the classical planets (Sun and Moon, and the planets Mercury through Saturn) have the upper hand. It also provides clues as to which planets will be more helpful or more problematic in the chart.