I will impart instruction by weight, and declare knowledge accurately: By weight apparently refers to the careful measurement of goods for sale; the meaning here is “precisely,” as New Revised Standard Version translates. The second line has practically the same meaning as the first one, so we may combine the two lines as follows:

• I will give you precise and accurate instruction.

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.