Don't want to meddle too much and let Jowy play his game, but I just want to point out a few things.
First is that Enchanted weapons are not buffable. I'd recommend upgrading one of your beloved Balder Side Swords (or any main weapon) along the normal path, and try buffing it with the Magic Weapon spell, Great Magic Weapon or it's even stronger variant when you get it. The buffs are worth it.
Speaking of buffs, that's where Ricard's rapier shines. Buff this rapier and hit the R2 button. Every hit will do the entire buff damage (a predetermined attack rating), which adds up even quicker than say, buffing a high damage strength weapon.
Important stuff: rapiers (the Estoc counts as one too) have a secret backstab/riposte damage multiplier. It may say 100 critical damage rating in the description, but it's not. Therefore I wouldn't dump your Estoc just like that; it has a backstab bonus which the BSS does not. If you're good at parrying/backstabbing, the Estoc (or any rapier) will definitely out-damage any katana, BSS and even matches the backstab damage output of the heaviest of Strength weapons. It's a feat not to be overlooked. Of course, this only goes for humanoid enemies, so pick your weapon wisely for different situations.
Also, rapiers can be used to attack from behind a shield. Not bad for a first playthrough.
And finally, the damage of rapiers, spears, the BSS strong attack and any thrust attack can be buffed by using the Leo ring, which you get from Ornstein if he falls last. The Leo ring buffs counters when
thrust attacks are used. This basically means: when you poke an enemy during it's attack animation, it adds up a crazy 40% damage. Watch this video for details on this underrated ring. With several buffs this guy does 1200 damage with a Ricard's rapier's
one-handed r1 from behind a shield. Dark Souls - Leo Ring (big counter damage) - YouTube
Soak up the wisdom