Analysis of information sources in references of the Wikipedia article "Troy weight" in English language version.
...the great fairs established for all Europe the weight-standard Troyes, whence...Troy...
The French livre contained, in the time of Charlemagne, a pound, Troyes weight, of silver of a known finess. The fair of Troyes in Champaign was at that time frequented by all the nations of Europe, and the weights and measures of so famous a market were generally known and esteemed.
The received opinion is that it took its name from a weight used at the fair of Troyes in France
...the great fairs established for all Europe the weight-standard Troyes, whence...Troy...