Off White/Analysis

The Spirit Colour Bar
From 0 (Poor Black) to 1 (Pure White), In This Order:

Pure Black(0):

 * Hati
 * Hugin

Mostly Black(0 - 1/4):

 * Raigho
 * Kaya

Somewhat Black(1/4 - 1/2):

 * Jerra
 * Albert
 * Othala
 * Isa

Somewhat White (1/2 - 3/4)

 * Fehu

Mostly White (3/4 - 1)

 * Gebo
 * Seven

Pure White (1)

 * Iki
 * Munin

What is the pattern here?