Source: Elison and Smith, Warlords, Artists, and Commoners: Japan in the Sixteenth Century.
Elison, "The Cross and the Sword: Patterns of Momoyama History," pp. 68, 299.
In 1576, Nobunaga had his own sword hunt in Echizen Province. The purpose was to separate the farmer from the samurai. The farmers job was to grow food and the samurai to fight. Nobunaga's vassal, Shibata Katsuie issued a seven-article document that ordered the farmers to the land and prohibited them from seeking new masters.
However, this was not Katsuie's own independent action. Nobunaga had full control of everything. This was a good idea since it disarmed the peasants and would make it harder for them to revolt. Twelve years later Hideyoshi would do the same in 1588. He probably took a page from Nobunaga book and expanded it.
Nobunaga was first to act before Hideyoshi and had full control. They had to get Nobunaga's blessings knowing full well Nobunaga would have complete control.
I would also like to know if any other Sengoku warlord did they own sword hunt.
Tenka no tame!