I've been trying to find this info on wikis, but have been unsuccessful.

Is it known how exactly Stat Bonuses affect weapon damage? For example, if I have Strength 30, how much does that increase a weapon's damage with a strength Stat Bonus rating of B vs one with C.

I don't know the math, but a B strength bonus would be higher than a C. The highest is a S with the full chart going E, D, C, B, A, S.

http://mugenmonkey.com/darksouls/weapons

That should have everything you need.

The letters doesn't translate directly to a certain number, they are more categories of ranges. Also, I might be wrong about this, but I do believe it's not even a flat number but rather a percentage of base damage. So it would be something like an A weapon will have around 100% bonus damage at capped stat bonus, while giving you about a 50% bonus at half-cap.

Thanks for this, great resource - I wish there was a way to modify the stat bonus though. Here is the situation that I am in - it is actually very similar to what happened in Episode 6 of Load our Last Souls.

Relevant current stats: Strength: 30; Dex: 20; Int: 16.

I have been playing the game with the Titanite Catchpole which I was lucky to get early on as a drop from the demon between Undead Parrish and Darkroot Garden, and I have even max leveled it up to +5. It has been a fantastic in general, but as I am progressing through the game I am noticing it is not as reliable against the tougher enemies who also have magic resistance as more than half of it's damage is magic based. So, I wanted to keep a normal weapon, maxed out for physical damage as a backup. Coincidentally like Vinny, based on my inventory I think I'm down to the Zweihander or the MSGS, with max physical damage being the goal here. I see that the MSGS changes the stats bonus for Strength from B to A after a certain point, so I was trying to decide between the two (or I'm open to suggestions).

Zweihander: Pros: more damage(?), closer in range to the catchpole which I am used to. Con: Slower in attack speed then the MSGS, possibly slower than the catchpole (unconfirmed).

MSGS: Pro: fast attack speed, drains less stamina, high strength scaling. Con: Shorter range than I am used to; less damage (?)

I'm leaning to the MSGS to vary things up a bit, but thought I'd put it out there for thoughts or other suggestions.

@thiago123: There are arrow keys to increase/decrease the stats from the default 40.

Thanks @turambar, but I am referring to the Stat Bonus (e.g. A, B, C, D for strength, etc), not the actual stat itself. Example, MSGS grants a strength stat bonus of B normally, but upgraded it goes to A.

It is likely that this isn't a raw number, like @ares42 said, so it's probably not possible.

The scaling bonus is not revealed as conveniently as it should. However, they are all incorporated to calculate the weapon stats anyways so there is no real need to know the weapon bonuses as long as you know what weapon you want to look at.

There is a formula for it all, however no one seems to have gotten it down perfectly just yet. Check here if you're interested. http://darksouls.wikia.com/wiki/Thread:10984

The general idea is that a weapon with better stat scaling (such as the MSGS's A strength scaling vs. the zwei's C strength scaling) is going to be better later on when you have the stats, whereas high-damage, low-scaling weapons are better early on. Some weapons just don't scale, and some don't get better scaling when you upgrade them. EpicNameBro has a video where he has maxed out every "strength weapon" and tested the max damage they can do on a darkwraith, his character having 50 strength which is the peak scaling point. I believe he determined that the demon greataxe was the strongest weapon in the game when maxed out under all normal circumstances. The MSGS ends up having more damage than the zwei in the long run, assuming you have high strength. Don't forget about the zwei's other semi-unique characteristic: the attack pattern of its strong attack is overhead, not a thrust. This overhead attack has an AoE knockdown effect as well, so even if you don't hit, you can stagger enemies.

There's also the fact that the Zweihander chews through poise and staggers most anything with just it's weak attack, and even some bosses with the strong. The Capra Demon can be sort of stunlocked with the two-handed R2.

If you are going PvE, I would say go Zweihander. If you want to get more into PvP, the Man-Serpent Greatsword may serve you better.

I'm kinda glad I chose 'correctly' with the Black Knight Greatsword. 611 damage, while not the highest, is still PREEEEEETTTY high

As long as you're picking a weapon that scales decently with your main stat, I think the weapon's move set matters more than final damage numbers. Can you get comfy with the range? Does it swing fast enough for you? Does it have a thrust attack for tight spaces? Do you feel BADASS when you use it?

Also, ANY all physical weapons will be better than a split damage weapon in a lot of cases. Split damage weapons have to go through 2 resistances, so their damage numbers can read higher than what they actually do.

All I'm reporting in here...maybe it will help someone else:

After much deliberation and testing a handful of different weapons/builds, I decided to go with the Zweihander! I could not get used to the shorter range of the MSGS after hours and hours with the Titanite Catchpole. While the +5 catchpole made short work of Nito, it was struggling with crystal warriors in Duke's Archives (I'm assuming they have high resistance to magic). A +13 Zweihander made most of the Duke's Archives a joke...and my god that strong attack knock down!! Once I broke out of the archive's jail cell and got to the warpable bonfire, I put everything on hold and went to get the last bit of materials I needed to get that sucker up to +15. Who cares about the slower attacks when you're one or two hitting every enemy I've faced since!

I did have a little bit of trouble with Seath's curses, but thats mostly because I tried to "Vinny it." I did summon a few phantoms a couple of times and apparently two handing the Zweihander + Grass Crest Shield on the back is a pretty popular combo haha. Five Four Kings, here I come!