Fine fettle

To be in fine fettle means to be in good order or good condition and the expression dates from the 18th century. Fettle as a verb, and now archaic, also means to prepare oneself for battle, and dates in this sense from the late 17th century. Originally, fettle is a Middle English word dating from the 14th century meaning readiness or preparedness. The etymology is from fetel, which is Old English for a belt or girdle, from which the meaning evolved to girding oneself, or tightening one's belt, in preparation for something or other.