Well, dex scaling might not be very good but I was able to get to rank 1 in BoB from SL130-150 with my dex character pretty fast. Powerstanced katanas.. yeah, I know. Beserker blade w/ poison resin + poison manslayer in offhand. Sometimes switching offhand weapon for estoc or small shield to parry. There's way more to katanas than their overused sprinting R1 attacks, and there's a lot of diversity when dual wielding them.
After getting rank 1 I switched to dual poison spotted whips and poison manslayer for kicks, and kind of feel like a piece of shit for using them, but I think I will continue to do so. It's so easy to poison with the powerstanced L2. Poison is great for those battles of attrition against chugging havel monsters.