Where does “crefti” come from?

crefti (Middle English) comes from Old English cræftiġ, from Proto-Germanic kraftagaz.

Ancestry of “crefti”, step by step

Step	Language	Word	Meaning
1	Old English	cræftiġ	ingenious; skilful; crafty; cunning; virtuous;...
2	Proto-Germanic	kraftagaz	—