Where does “on-handed” come from?

on-handed (Middle English) comes from Middle English on-hande, from Old English ān-hende — one-handed.

Ancestry of “on-handed”, step by step

Step	Language	Word	Meaning
1	Middle English	on-hande	—
2	Old English	ān-hende	one-handed

on-handed — Etymology, Origin & Word History | Etymology Explorer