E. Cobham Brewer 1810–1897. Dictionary of Phrase and Fable. 1898.
Duc’at.
A piece of money; so called from the legend on the early Sicilian pieces: Sit tibi, Christe, datus, quem tu regis, istë ductus (May this duchy [ducat-us] which you rule be devoted to you, O Christ).
tus (May this duchy [ducat-us] which you rule be devoted to you, O Christ).
