User blog comment:Project Predacon/Volume 2: Post Credits Scene Analysis/@comment-25110963-20141031012224/@comment-24891101-20141031013629

It's almost certainly her Semblance. Semblance is an extension of Aura, after all, and Aura is channeled through weapons. Weiss interacts with her glyphs via her rapier, after all. Nothing about Remnant's technology suggests that they have portable wormhole generators; that's too advanced for the setting.