Is it possible to tell which of two similar weapons are better than one another? As in a command?
Or is it just trial and error?
Trial and error. The 'compare' idea has been around for some time but never implemented, so I can't say for certain but I think there's a code issue with getting it done, otherwise I assume it would have been done a long time ago.
OR it just got pushed down the list, priority wise, perpetually, because that kind of thing can happen when you have lots of cool stuff you want done.