Will we ever learn more about the incident which gave Gaius' gunblade its name, in which he slew nine aspirants to the crown of Garlemald?

For example, how long ago did it happen? Who were the nine people killed in the incident? Were they all actively treacherous towards Emperor Solus, or were they simply Solus' extended family who had a claim to the throne? Did Emet-Selch (as Solus) order Gaius to kill them, or was it something that Gaius did on his own?