Thanks Gav and 'Nando
,
I was thinking of the less sophisticated version posted by Fernando. Gav the example you posted suggests that some sword breakers were a 'dedicated' weapon. I had assumed that the Sai 'type' were used like a 'main gauche' with a sword (or similar) held by the other hand. I know in Martial art 'forms' ....the Sai is used on its own or in pairs......but I cannot imagine an individual, on a battlefield using two, as his main weapon of choice.
Kind Regards David