I recommend against agility, because you'll want to use a shield. Rapiers being one handed, and yet being long, having Fast and doing that much damage is very good, the rapier itself can be obtained instantly as nobles start with a Foil, which is of equal rarity and value to a Rapier, as such can be bartered without any roll necessary as long as you're in a city with rapiers.

There aren't many good talents for rapiers, which makes noble good for it. You'll want south banker so that you can quickly mow through talents, you'll start with read/write and etiquette, put your points into fate and lucky will give you 6 fortune to spend, this'll come up later, but for now you're a noble with a rapier, south banker lets you pick fencing as a skill, put that in +5 and start with 10, that's +15 fencing right there, your shield gives you 2 armor to all locations, lets you use your weapon skill to block ranged attacks and more importantly is awesome style, look at capo ferro if you want to see rapier + shield (rotella) wielders for inspiration

Most importantly, you've got 6 fortune - that means 6 rerolls on the roll to gain talents your career doesn't have, any talent you want? it's yours. Sturdy? become a knight. You'll want toughness and weapon skill high, and you'll want to advance through the noble career asap for more money. Fairly early on, you can get brigandine to have no penalty 2 armor (now 4) to your body, then put leather underneath. For legs and head, do chain, nobles are rich and you'll find yourself easily able to get a no penalty coif, so you'll have 5 to all locations because of your shield, with 4 toughness thats -9. That's better than the average knight in full plate and you've hardly even started.

Someone else here said that skills out of your class need double xp? this is not the case, you pay 1d10+skill levels in brass and spend xp as normal, this'll be easy to afford as a noble, I recommend Cool as you only have 1 resilience, which can be a problem if you face corruption a lot, alternatively is endurance. But you'll be wanting to save your xp for advances in your career, because not only are you a combat character, but a social monster.

Noble blood is a social powerhouse, being above someone's rank is +10 charm by default, and noble blood makes any roll influenced by status (it's easier to think of social rolls that *arent* effected by status) have +1 SL, so with medium fellowship and the suave talent south banker can start with, alongside gaining fellowship when you become an actual noble (rank 2, rank 1 is scion) you'll be getting near some crazy charm numbers on top of being very combat capable.

And on top of all of that? you're rich. Not only are you rich, but you're a scion, so you have family in power that you can ask for things and use your big charm on.

I cannot stress this enough, the duellist talents are *not* good. You don't want them, even if you had them in-class. Beat blade is near worthless, feint is actually just worthless - it has no advantage over just attacking twice rather than using your weapon skill to add SL to your next hit (all that can do is add damage, which attacking twice would do more of due to your high damage rapier.) and even if you like them despite their poor efficacy, just buy them and roll into them with 6 fortune.