“two-thirds of a shekel.” The Hebrew word is “pim,” and it occurs only here in the Old Testament. Older versions took an educated guess at the meaning and some have “file,” (cp. KJV), but that has proven to be wrong. The verse is saying that the Philistines charged for the service of sharping metal instruments, and the price was not cheap for those times. Archaeologists have now found stone weights marked pim in some excavations, and the weights are roughly equal to two-thirds of a shekel, about .26 ounces.
“to set the goads.” That is, to set the metal points on the ox goads.