Kingships and the Tzadik

ולאום מלאום יאמץ refers to the kingships; at times Eisav is greater; other times Yaacov. ורב יעבוד צעיר refers to individuals where children of Yaacov are always greater. Thus, Kings of Edom were not from Eisav. Sometimes necessary for the Tzadik to lower to the level of Kelipah temporarily in order to elevate the Kelipah.