Two Questions - 1) How many Titanite Chunks do you need to finish a weapon's upgrade path AND 2) is there any way to get them apart from the Bell Bros? I know you need the Slab for +10, but how many Chunks do I need to go from +6 to +9? I spent some time defending Belfy Luna last night and, for me, PvP just isn't as satisfying as Co-op. I mean, it was a fun distraction, sure. I probably won about as many duels as I lost. It just isn't as enjoyable (to me, at least) to hinder people rather than helping.
Trade with the Dyna and Tillo the crows (random) Buy from Stone Trader Chloanne, 6000 each. (10 limit after king's ring is obtained, unlimited at end game) A chest in the Shaded Woods after the third bonfire (Shaded Ruins - the one just after the fogged area). After fighting the first two lion warriors, move up the ramp and turn around, then jump across the gap to a chest that's easily visible. There's a Petrified dragon bone in the chest, aswell. In the Forest of Fallen Giants Cardinal Tower bonfire, In the room to the right just before Pate with the 4 big ballistas pointing at you, below is a chest that will contain x1 Titanite chunks (Note: 3 on NG+ or if Bonfire Ascetic has been used) (this is wrong, I Haven't tested in NG+ but in NG there is only a titanite shard , no chunks in that place). (Tested and True, in NG+ there are 3 Titanite Chunks). In the first poison pool in Harvest Valley, the rightmost item is one Titanite Chunk.
Dropped By Large Gyrm at Doors of Pharros. Dropped by Coal Tar in Black Gulch (beasts that hide in the small pools) 5% chance of titanite chunk, 10% chance of large titanite The Undead Peasants in Brightstone Cove Tseldora, 3% chance
I believe it goes 1 for +6, and then 2 for +7, 3 for +8, and 4 for +9, so in total 10 chunks to get from +5 to +9 EDIT: Yeah, this part is wrong, sorry.
You can get titanite chunks from co-op, it just isn't very reliable. Just use your small soapstone, and trade the silky stones with the crows.
Eventually you can buy them (limited supply, 10).
They're a fairly common drop from the big Gyrm guys in Doors of Pharros.
Awesome, that is great to know. If I only need 6 per weapon/armor piece, I can probably stand to be an obstacle for other players for a little while longer. PvP isn't normally my thing, but I have to admit that there were some pretty fun moments.