In Operation Luna, when his daughter, Valeria, has turned fifteen, Steve says:
"Transcosmic expeditions had been mighty few, I recalled. Some had never been seen again."
-Poul Anderson, Operation Luna (New York, 2000), p. 337.
In A Midsummer Tempest, Valeria, an adult, travels between universes, knows how to assess parallel Earths and has found the inter-cosmic inn, the Old Phoenix.
Thus, scientific progress accompanies the growth of the Matuchek family.
I find the pompous talking sword unbelievable. However, if Operation Luna were to be filmed, then its/his shining surface should pulsate and change color in synchronization with his speech. This would be slightly more acceptable that an apparently disembodied voice accompanying an inactive weapon.