In truth, Viktor was only one of three Canthan heroes who had to cooperate to beat Shiro. The assassin Vizu first used her Shadow Arts to disarm Shiro. Then, Viktor and the Luxon champion Archemorus together killed Shiro with his own blades.
Warning: The following text contains spoilers relating to the plot of the Factions Campaign.
The Urn of Saint Viktor is kept by House zu Heltzer as a family treasure in Cathedral zu Heltzer. Holding it charges its skill. Note that he is wearing the 15k Kurzick Armor that is available to warriors at the armor crafter in Vasburg Armory.