Tuhui: btw if you have had AP or Sentenza you know that it is 2 supper effective, 2 less than normal, 2 weak.

It's seems impossible to get reliable numbers, because there are a lot of variables that affect things and all the mechanics are SECRET, but the available data suggests that 50% strong and 50% weak damage should approximately cancel out and do basically the same as 100% normal. Just looking at the color of the damage when using a mixed-type weapon doesn't mean anything, the damage colors are obviously severely buggy, even the exact same weapon against the same enemy doesn't always produce the same color.

In this particular case, though, the Cautery Sword is obviously intended to be a hyper-specialized weapon, so I don't even care if split strong/weak is worse than normal. My suggestion is the same.

@DrLequack: Also; bear in mind the royal jelly has different defense than regular slimes. The cautery may deal more than a nightblade to it.

Yes, the JK is not weak to shadow, and I don't think the royal minis are either. I haven't specifically tested the Cautery Sword against them; if they count as slimes despite ignoring normal slime rules (unlike Vanaduke, who doesn't count as undead), that's STUPID and grossly misleading, but it would mean (based on stats I've seen on the wiki and forums) that the Cautery Sword would maybe do 10% more damage against them than the Nightblade. At the cost of about 20-25% less damage against all other slimes AND a little bit less against everything else in the Jelly Palace. And the comparison gets even worse if you have damage bonuses from anything else (wolver, bristling buckler, trinkets, UVs...) both because of the multiplier effect and, potentially, because of the bonus cap.

That would be an insulting trade-off even if the upgrade path wasn't a dead end. Especially since, if you're willing to choose your weapon based only on its effectiveness against the Jelly King himself, you'd be a fool not to choose one with Poison.

Sounds roughly in line with the numbers I've seen in test threads, which are about 7-8% bonus per rank of increased damage (so ~30% for "very high"), and a 67% increase for damage types the target is weak against (which only applies to half the damage in your example, so about 33% overall, probably between "very high" and "ultra").

But the Cautery Sword also appears to have lower base damage. The wiki doesn't have damage numbers for any of the other 3* brandishes, but if we compare it to the Tempered Calibur (3*, 100% normal, similar attack pattern), the Cautery Sword appears to do about 12% less against most enemies and only 5% more against slimes, which is frankly ridiculous. That actually means the numbers in my previous post probably made the Cautery Sword look BETTER than it truly is.

If the entire damage was multiplied by 1.5 for the weakness and then by 0.5 for the resistance, that would be 75% overall. But that would be stupid and there is no indication that it works like that.

The more sensible way, and the way it appears to work, is that the different damage types are calculated independently and then added together. So if half your damage is multiplied by 1.5 and the other half by 0.5, you're doing (1/2)*1.5 + (1/2)*0.5 = .75 +.25 = 1.0 = 100%.

Not that weakness or resistance actually equates to a 50% change, just running with your example.

As for the colors, as I said, they're clearly bugged. Sometimes the monster will appear weak to my first attack but neutral to my finisher with the same weapon, other times vice versa. The same monster that appears weak at one depth appears neutral to the same weapon at another. I've heard several reports from people who have used split damage weapons that strong+weak does approximately the damage of normal but is displayed in gray.

If you want to figure out how things work, you need to look at the actual numbers, not the colors.