Into the Wardrobe

I have a very simple answer to this question:

The Dufflepuds' weapons become visible when they do because perilously materializing weaponry is dramatic. The dishes remain visible because soup tureens bouncing inexplicably is funny. Logic need not enter the picture.

And to coin a Dave Barry-ism, either The Perilously Materializing Weaponry or The Bouncing Soup Tureens would make a great name for a rock band.