Where does “arst” come from?

arst (Middle English) comes from Old English ǣrest, from Proto-Germanic airist, from Proto-Germanic airi, from Proto-Germanic airiz — earlier, before; comparative degree of *airi.

Ancestry of “arst”, step by step

Step	Language	Word	Meaning
1	Old English	ǣrest	first, erst, at first, before all; earliest
2	Proto-Germanic	airist	earliest, at first; superlative degree of *airi
3	Proto-Germanic	airi	early
4	Proto-Germanic	airiz	earlier, before; comparative degree of *airi

Every word from Proto-Germanic airiz →