Which Katara will help me deal more damage?

[IllegallySane]

So I have a level 64 Katara and am using a level 77 one.

The 64 has the following relevant stats:
39 attack
+4% crit
15% ignore defense

The 77 has the following relevant stats:
50 attack
+6% attack

Is Ignore Defense powerful enough that it actually beats the level 77 one with more attack?

[SaptaZapta]

No.

[Green4Ever]

% Ignore Defense really isn't all that noticeable except on mobs with good amounts of PDR, so I would go with the Level 77 one.

[Curtiss]

As mentioned, go for the level 77 one. PDR is not subtracted directly from enemy defence so it's only good on monsters with very high PDR (> 50%) as you'd basically be taking off 15% of the actual PDR instead of subtracting 15% straight. Most mobs of your range only have about 5 - 10% PDR so 15% of that is only about 0.75- 1.5%.

[IllegallySane]

As mentioned, go for the level 77 one. PDR is not subtracted directly from enemy defence so it's only good on monsters with very high PDR (> 50%) as you'd basically be taking off 15% of the actual PDR instead of subtracting 15% straight. Most mobs of your range only have about 5 - 10% PDR so 15% of that is only about 0.75- 1.5%.

Oh wow, good lord. I thought it was a flat reduction, which would make it so awesome. Seeing it's multiplicative it's not as great. A bit surprised that mobs at my 128 range still only have about 10-15% PDR. As for why I'm still using 8x weapons, I made the Dual Blade to be DEXless and only now have I given her some gear upgrades so she can eventually use stronger stuff. To be fair, a DB with 8x gear is still kicking major ass for me.

From what I got from a quick glimpse at the datbase, the only monsters/bosses with PDR as high as the 50%+ range are mobs/bosses involved with Chaos Zakum, Pink Bean, Cygnus, and Azwan. I assume then that THE biggest damage boost I can possibly get is +30% boss damage.

[Curtiss]

Oh wow, good lord. I thought it was a flat reduction, which would make it so awesome. Seeing it's multiplicative it's not as great. A bit surprised that mobs at my 128 range still only have about 10-15% PDR. As for why I'm still using 8x weapons, I made the Dual Blade to be DEXless and only now have I given her some gear upgrades so she can eventually use stronger stuff. To be fair, a DB with 8x gear is still kicking major ass for me.

From what I got from a quick glimpse at the datbase, the only monsters/bosses with PDR as high as the 50%+ range are mobs/bosses involved with Chaos Zakum, Pink Bean, Cygnus, and Azwan. I assume then that THE biggest damage boost I can possibly get is +30% boss damage.

I thought exactly the same thing as you before until someone corrected me which was when I went "What, so you mean Marksmanship does not in fact make me deal 25% more damage!?" And yes, 30% boss basically means something like this:

Take a 50% PDR mob. Let's assume you deal a fixed damage of 20 k for this and let's say you have either 30% PDR or 30% boss.

30% PDR x 50 = 18% so you deal 10k (1/2*20) + 1.8k damage= 11.8k.
30%*10k= 13k.

There are however circumstances where PDR gives you more bang for the buck, such as at Cygnus (70% PDR, I think?).

[ElderTree]

% Ignore is added together from all sources (Ambition, Potential, Codex, etc.) and then multiplicatively reduces the PDR of a mob. So if you have 30% Ignore from Priere D'Aria, 15% Ignore from Hob PQ codex set bonus, and 2% Ignore from Ambition, you have a total of 47% Ignore.

Normally, a boss with 70% PDR (PB/Empress) will make you do 30% of your normal damage (1-0.7 = 0.3). However, with 47% Ignore, you're looking at 1-(0.7*(1-0.47)) = 0.629 = 62.9% of your normal damage. That's an increase in damage of x2.097!

Due to the multiplicative nature of the PDR reduction, any % Ignore over 100% is useless.

I thought exactly the same thing as you before until someone corrected me which was when I went "What, so you mean Marksmanship does not in fact make me deal 25% more damage!?" And yes, 30% boss basically means something like this:

Take a 50% PDR mob. Let's assume you deal a fixed damage of 20 k for this and let's say you have either 30% PDR or 30% boss.

30% PDR x 50 = 18% so you deal 10k (1/2*20) + 1.8k damage= 11.8k.
30%*10k= 13k.

There are however circumstances where PDR gives you more bang for the buck, such as at Cygnus (70% PDR, I think?).

Using your example vs. a 50% PDR boss:
* With:(0% Ignore, 0% Boss) = (1-(0.5*(1-0))) * 1.0 Boss = 0.5 = 50% of your "normal" damage
* With:(30% Ignore, 0% Boss) = (1-(0.5*(1-0.3))) * 1.0 Boss = 0.65 = 65% of your "normal" damage
* With:(0% Ignore, 30% Boss) = (1-(0.5*(1-0))) * 1.3 Boss = 0.65 = 65% of your "normal" damage
* With:(30% Ignore, 30% Boss) = (1-(0.5*(1-0.3))) * 1.3 Boss = 0.845 = 84.5% of your "normal" damage

Or, more concretely, if you averaged 20k as your "normal" damage, then you'd be doing 16.9k vs. the 50% PDR boss.