J.H.M.
To Fetyl, v. n. To join closely. See G. factil. ligamen.—Wyntown.
Fettil, Fettle, s. Energy, power.—S.B.
To Fettle, v. a. To tie up.—S.
Fettle, adj. 1. Neat, tight.—S.B. 2. Low in stature, but well-knit.—S.B.
Fetous, adj. Neat, trim.
Fetously, adv. Featly.
Jamieson's Dictionary, abridged 8vo. edition. Fettle, v. To put in order, to repair or mend any thing that is broken or defective.
I am inclined to consider it as from the same root as Feat,—viz. Sue Got. fatt, apt, ready. Swed. fatt, disposed, inclined; fatta, to comprehend.—Brockett's Glossary.