Until recently our knowledge of the background and early function of this blessing outside of the Book of Numbers was rather limited. This was largely due to the paucity of evidence for the blessing in ancient Judah dating to the Iron Age (ca. 1200–586 BCE). The discovery of several Iron Age inscriptions from the regions of Syria and Palestine, however, has begun to shed new light on the early function of the blessing.Also, some thoughts on the use of the blessing against demonic evil.
Past posts on Jeremy Smoak's work on the priestly blessing are here and here. Other past posts on the Ketef Hinnom silver amulets (which contain a version of the priestly blessing) and the priestly blessing itself are here (cf. here and here) and links.