Equip the Golden Serpent ring, go to Anor Londo, kill Silver Knights until they drop the Silver Knight Spear. Then go to the Giant Blacksmith and buy 9 twinkling titanites to upgrade it to +5. You now have fantastic melee damage for a dex build and only had to farm one area. If you're low on souls for the upgrading process, you can go kill the guardians next to the Darkroot Garden bonfire over and over for 7,000 souls per 2 minutes or so. If you happen to have the Silver Serpent ring, it'll be 8,400 per run. The spear is a holy weapon, so if you wanted to make the run to get the ring from Tomb of Giants, it wouldn't be entirely unreasonable to attempt it, but that's optional.