My only tip:
If he is noble, b ut won?t receive any benefit of it, make just a note on the character background.
Now if hes going to see some real advantages, like:
* The right to speak to scheddule appointments with the Nobility.
* Being invited to events like parties, dinners etc.
* Special legal rights, like nobles can only be judged by nobles, or noble cannot be arrested by the common militia.
Remmember Nobility must be advantage in order to soct DPs, but usually its a social advantage, not necessarily a monetary one. The son of a rich merchant can have way better starting equipment.
Personaly I would charge extra DPs for Masterwork gear (+5 bonus weapon, or PP adders for example).
In my current game the party?s Knight used his nobility at least 3 important times during the campaign, and the most important one was keeping the party out of an arranged/fixed evil arrest.
Remmember: in medieval societies you do NOT have acess to the Royal Family, specially to the King if you are not a noble. But if you do not plan to use these limitations to the common folk, I suggest do not charge for the Nobility in DPs, charge only for any special starting itens.
Best regards.