"If you don't care about science enough to be interested in it on its own, you shouldn't try to write hard science fiction."
- Frederik Pohl

Appropriately, Lazarus Long, eldest member of the Howard Families, uses the traditional weapon rather than the new-fangled version.

These quotes are taken from the expanded versions of these stories from the collection The Past Through Tomorrow; both of these stories were expanded from their initial publication in 1940 and 1941. I haven't been able to confirm the presence of the word "vibroblade" in the original publications.

For purposes of comparison, Randall Garrett wrote this about the vibroblade in his 1962 novel Unwise Child:

A vibroblade is a nasty weapon. Originally designed as a surgeon's tool, its special steel blade moves in and out of the heavy hilt at speeds from two hundred to two thousand vibrations per second, depending on the size and the use to which it is being put. Make it eight inches long, add serrated, diamond-pointed teeth, and you have the man-killing vibroblade. Its danger is in its power; that shivering blade can cut through flesh, cartilage and bone with almost no effort.