A modest wife adds charm to charm: The wife is described here as modest; that is, she is someone who knows what ben Sira regards as her proper place, and who keeps to it. She does not put herself forward or call attention to herself. For adds charm to charm, Good News Translation does well with “has endless charm.”
And no balance can weigh the value of a chaste soul: While it is possible that the Greek is talking about “chastity” (New Revised Standard Version) in the sense of sexual fidelity, it is more likely that chaste is here a synonym for modest. This is why Good News Translation expresses the idea by referring back to the first line as follows: “it [the wife’s modesty] is a quality….” The balance refers to scales, a device used to weigh items, especially bits of precious metal, to determine their value. Good News Translation expresses the idea without referring to the device by rendering no balance can weigh as “too precious to measure.” We may also translate the whole line as “it has a value that is impossible to measure.”
Quoted with permission from Bullard, Roger A. and Hatton, Howard A. A Handbook on Sirach. (UBS Helps for Translators). New York: UBS, 2008. For this and other handbooks for translators see here.