Middle English word wis comes from Proto-Indo-European *wéydtus, and later Proto-Germanic *wīsaz (Wise, knowledgeable.)

Detailed word origin of wis

Dictionary entry	Language	Definition
*wéydtus	Proto-Indo-European (ine-pro)
*wīsaz	Proto-Germanic (gem-pro)	Wise, knowledgeable.
wis	Old English (ang)	Wise.
wīs	Old English (ang)
wys	Middle English (enm)	Wise.