The qualifying children will be given the weapon of their choices from those listed in the items for Arena 12. They will loaded into their pods with their item of choice, and begin the Arena already armed.

This will be a handwaved process and there's no need to wait for further verification from a mod. Go forth and murder, children.

(Also we'll be adding this to the Arena info so that everyone to which it pertains is sure to have a chance to see it. Thank for the question, this was a good one.)