Harangue

NG+whatever onward fights hardly have anything to do with your weapon anymore, it's all just a matter of your skills as a player. If you want a new weapon your best option is finding the one that overall deals the most damage at that point when fully upgraded. Really, you're just going to spend a lot of time dodging or blocking anyway. With bosses with so much health it's all a matter of having mastered their tells and having the time to waste wittling down their HP.

I realize this is an old topic, but I'd like to leave this for anyone who may come upon this in the future.

I think most players who weren't introduced to DaS through DeS felt like they were just pissing in the wind when it came to damage at first.

1. With STR or DEX below twenty, weapon scaling damage is usually quite paltry, so feeling weaker is to be expected. Look at all the weapons you pick up and see what their Scaling (below ParamBonus in the weapon's Stats) is graded at. Really early, you'll probably only have Grade C, but a little further in you'll find B and A, and very rarely, S scaling weapons. Try to find a weapon with a moveset you like as well as one with a good scaling grade. For instance, with high Dexterity, you'll probably want to go to Blighttown and find the Falchion as early as you are able. It has A grade scaling with Dex.

2. The Prowling/Titaninte Demon, which is that one-legged thing, is not required to progress, and there are quite a number of them in the game. Most people skip him the first few times. I usually don't fight him unless I have good ranged damage, or have high enough END to block his swings. He drops Demon Titanite, which unless you're using a Demon Weapon (which you won't have access to unless you either got lucky at the Asylum/Taurus/Capra or bought one from Shiva in Blighttown, or forging some boss weapons in Anor Londo) is totally worthless to you to even pick up. In fact unless you use a Demon weapon, the only real reason for you to kill it is for a few measly souls and so that he's not in your way between Darkroot and the blacksmith.

2. If it's your first playthrough you're better off just raising weapons to +10 and advancing them to Lightning damage or Fire damage aspect.

Catacombs is perfectly viable without Divine weapons. Honestly I only ever used a Divine weapon twice, and that was my first time through and again with a squishy DEX build. It's incredibly easy to sprint through or turtle through and just slay all three of the Necromancers and Pinwheel. People often do it early in the game to get immediate access to the Rite of Kindling.
Only issue I could really see would be the three little knob-gobblers hanging around with Nito.

This thread actually answered my question multiple times. I am making a new build and my misinformed friends all kept telling me to put some points into DEX for seemingly no reason even though I told them I'd be using STR weapons. I knew most of them were wrong, but I wasn't sure if DEX had a secondary effect I wasn't aware of.