Editor was once a Latin word meaning one who puts forth. That's why the chap or chappess who puts forth a book came to be known as an editor. As the putter-forth of a book usually has to make some alterations we then got our familiar verb edit. As those alterations are usually deletions, edited has come to mean cut.
However, it's worthwhile remembering that editor only got attached to books by coincidence. Etymologically, somebody who threw you out of a nightclub or a window could have been called an editor. Moreover, the original Roman editors were much more brutal people.
In the high and palmy state of Rome the Editor was the man who put out the games at the Colosseum. He obtained the Christians, the lions, the gladiators and decided, in his pomp, which would live and which die. A couple of descriptions will help:
The editor giving the games, usually to curry political favor with the mob, rode behind on a chariot perhaps drawn by exotic wild animals such as zebras or even ostriches.
If the emperor was not in attendance, the producer (editor) of the games decided the fate of the victim. Even if defeated, a gladiator might be granted a reprieve (missus) if he fought well or, if neither fighter prevailed, both could be reprieved stans missus. But a gladiator also could be forced to fight again the same day, although that was considered bad form, and there were contests in which no reprieve was granted the loser (sine missione).
Ask any writer: nothing has changed.
The Inky Fool asks whether something should be cut