1)
What is "Nir"?
1.
Rashi: It is authority. It is an expression of a yoke.
2.
Radak: This is like Ner with a Tzeirei (a lamp), like "Arachti Ner li'Mshichi" (Tehilim 132:17).
3.
Radak citing Targum Yonasan: It is 'Malchu' (kingship). Targum Onkelos of "va'Niram" (Bamidbar 21:30) is 'u'Malchu'.