Hittite arma 'moon'

The etymology of Hittite arma 'moon' seems to be obscure....


In PIE we have:

a) méh1-n-o:t [gen.] meh1-n-és 'the measure/the measurer' -> 'moon, month' < PIE meh1- to measure

b) *louk-s-neh2 'the shining one' < PIE *leuk-

c) *(s)kond-/(s)kn.d- 'the shining one' too < PIE *(s)kend-


Hitt. arma 'moon' (< 'the measurer'?) < *h1or-mo was linked with Tocharian yärm 'measure' < *h1ermn.

from
a) h1er- 'to put in motion, to arise' > h1or-mo > arma
b) or from 'a new' root h1er- 'to measure' (Adams)

Any comment here?

Thanks,
Marius