arkangelii is the singular partitive or singular partitive of Arkangeli.

ArkangeliN

Norwegian Bokmål

ArkhangelskN

Kven – Norwegian Bokmåldict-fkv-nob/src/Prop_fkvnob.xml:251Edit on GitHub Suggest

Case	Sg
Nom	Arkangeli / arkangeli
Gen	Arkangelin / arkangelin
Par	Arkangelia / Arkangelii / arkangelia / arkangelii
Ill	Arkangelhiin / arkangelhiin
Ine	Arkangelissa / arkangelissa
Ela	Arkangelista / arkangelista