How about, instead, in the Codex, you can hit "test this weapon" and then there's a miniature "battle", where the weapon is mounted on a cool-looking test stand, and a target object / objects is available to blow up?
This would be far simpler (it's basically just a Mission where the "player ship" is an immobile object, after all) than building "official content" for weapons that might or might not make the final cut, get changed in ways that are no longer reflected in the static data... and what about mods, etc., etc., etc.
Basically, the idea of, "hey, you can test out all the things in the Codex for free" is not terrible, but "hey, we should add lots of new content hassles to a game that's trying to stay on a shoestring" is not.
Oh, and this concept's almost doable right now with a mod, except that we can't access the Codex or tell when we're in that state explicitly.