There are 3 possible modes of operation:
Turning the weighted phrase feature completely off will lobotomize DansGuardian from "true" (or "content") web filtering to little more than fancy (including regular expressions) URL filtering supplemented by banned phrases and the possibility of modifying content, which isn't very different from much simpler web filters.
DansGuardian supports two different methods of calculating weight scores, the "normal" method and the "singular" method. Each method has its pros and cons. Very good webpages will score well with either method, and very bad webpages will score poorly with either method, but middling webpages may score below your threshold with one method but above your threshold with the other. So don't change an established DansGuardian system to use the other method lightly.
Also, the two weight scoring methods may require slightly different "naughtyness" limits in order to behave similarly. If the value you've chosen for "naughtynesslimit" is just a rough guess, it won't matter. But if you've tuned "naughtynesslimit" within a margin of only 5 or 10, you may need to re-tune it after you change the weight scoring method.