Where does “ch'et'adhi” come from?

ch'et'adhi (Lower Tanana) comes from Lower Tanana -i, from Lower Tanana yo, from Proto-Athabaskan *yaˑ — sky.

Ancestry of “ch'et'adhi”, step by step

Step	Language	Word	Meaning
1	Lower Tanana	-i	A nominal suffix for non-human nouns with the meaning of 'the one who...,' 'with it [verb] is done.' Used to derive nouns from verbs, adverbs, and other nouns
2	Lower Tanana	yo	sky
3	Proto-Athabaskan	*yaˑ	sky