Ice weapons were at first used in the Northern Kingdoms. They were ancient weapons, dating back to the time before King Hoole and continued use even after the reign of Coryn. They didn't come to the Southern Kingdoms until the reign of Boron and Barran. There was no need to keep the weapons, because they melted more easily in the warm southern climate and it was too much trouble to keep them safe. And the invention of Theo's battle claws made them unecessary for the Southern Kingdom owls. They only reappeared when the band brought them back during the Battle of the Burning. The first time owls from the Southern Kingdoms used them was when Ruby used an ice scimitar to slice off the wings of two kraals, Krakish for pirates.