Viper would of been better if it had a different name

[Iscah]

The difference is those names allude to the form of combat they utilise in a way that Viper does not. Gunbreaker implies gun, at least...

"Gunbreaker" implies fighting *against* someone with a gun, and indeed is the in-game etymology (probably invented to justify the name) provided to you when you take up the job.

You keep saying that these job names clearly indicate what they do because there is precedent for it in older FF titles, but I don't think that counts. There was a point in time where each of those was a fully new job with no history to it.

If red mage was brand new now, people would be complaining about how unimaginative another "colour mage" is and how it makes no sense that black+white magic = red, and they should have called it something that conveys the job better.