[Endoperez]

In Dom1, to rename a commander:

In his info screen (right-click opens that), press r. Or maybe shift+r.

And, that was removed because of three armies led by PowerMonger the Frost Father/ Sea Father/ Ice Druid. Or somesuch. You could get your enemy wondering unless he knew all available pretenders. Or because a pretender was renamed!

Only way I can think that would remove the need of this would be if pretenders/prophets etc. were very clearly named in scouting reports, commander types were mentioned in there AND in Hall of Fame. And even then this might not be enough.