It is actually pretty good, all by itself. And, doesn't need anything much if it is only one level.
What I'd do is add some flavour- the Noble has a +2 circumstance bonus to all skills that relate to his area/nation. That is- History, Nobility, Diplomacy, Area knowledge, Intimidate, gather Information etc- and one bonus language that is common in his land. This relects the fact he is better known, has met the areas Nobles, etc. But this all works only in his Kingdom- not some Empire a continent over. And, this +2 adds to his Leadership feat, when he gets it.
And of course, being a Noble might come in very handy in some cases. Most Nobles get free "guest privlidges" fro a few nights at other Nobles in that Kingdom- saves inn expenses.
I'd also add free weapon focus in the "prefered weapon of Nobles" in his area. Rapier, Longsword, scimitar- whatever is so de riguer that nearly every noble in that Kingdom carries one. And, of course a free MW weapon of that type (which replaces the regional free item you get from FR, etc). Thus, he has the same BAB as a fighter at 1st level- but only with one weapon.
Maybe, just maybe, a free feat at 6th, which could be Leadership or a few others.