Fettle
Condition or fitness. Can be thought of as an analogue to mettle, but regarding **f**unctional rather than **m**aterial qualities. Fettle is how something is made in contrast with mettle being what something is made from.
Found in the 25 January 2014 edition of *The Economist*. The former military dictator of Pakistan, Perez Musharraf, was described by doctors as being in «pretty good fettle» despite claims of a heart attack for which there was no evidence, and upon which his lawyers claimed he was not healthy enough to be tried for high treason.
Thanks go to *The Economist* for expanding my vocabulary, a task other publications seem reluctant to take on.