Where does “vansæll” come from?

vansæll (Old Norse) comes from Old Norse van-, from Old Norse vanr, from Proto-Germanic wanaz, from Proto-Indo-European h₁weh₂- — to leave, abandon, give out.

Ancestry of “vansæll”, step by step

Step	Language	Word	Meaning
1	Old Norse	van-	under-, un-
2	Old Norse	vanr	lacking, wanting; a member of the Vanir
3	Proto-Germanic	wanaz	lacking, deficient, absent; accustomed
4	Proto-Indo-European	h₁weh₂-	to leave, abandon, give out

Every word from Proto-Indo-European h₁weh₂- →Every word from Proto-Germanic wanaz →Every word from Old Norse vanr →