These are my settings:

bothPrefixSuffixModifierBoss,3000.000000,
bothPrefixSuffixModifierHero,2500.000000,
bothPrefixSuffixModifierHeroChest,2000.000000,
bothPrefixSuffixModifierChampion,50.000000,
bothPrefixSuffixModifierChampionChest,25.000000,
bothPrefixSuffixModifierCommon,25.000000,
brokenOnlyModifierBoss,0.000000,
brokenOnlyModifierHero,0.000000,
brokenOnlyModifierChampion,0.000000,
brokenOnlyModifierCommon,375.000000,
noPrefixNoSuffixModifierBoss,0.000000,
noPrefixNoSuffixModifierHero,0.000000,
noPrefixNoSuffixModifierChampion,500.000000,
noPrefixNoSuffixModifierChampionChest,250.000000,
noPrefixNoSuffixModifierCommon,1500.000000,
noPrefixNoSuffixModifierCommonChest,750.000000,
prefixOnlyModifierBoss,0.000000,
prefixOnlyModifierHero,0.000000,
prefixOnlyModifierHeroChest,500.000000,
prefixOnlyModifierChampion,100.000000,
prefixOnlyModifierChampionChest,50.000000,
prefixOnlyModifierCommon,50.000000,
prefixOnlyModifierCommonChest,100.000000,
suffixOnlyModifierBoss,0.000000,
suffixOnlyModifierHero,0.000000,
suffixOnlyModifierHeroChest,500.000000,
suffixOnlyModifierChampion,100.000000,
suffixOnlyModifierChampionChest,50.000000,
suffixOnlyModifierCommon,50.000000,
suffixOnlyModifierCommonChest,100.000000,

But champions still wear broken items occasionally. I also tried changing the 0 values to 1 in case it didn't accept putting them to 0 for some reason, but that wasn't it either. I also noticed the mermen outside Corinth dropped white items a LOT more often than, say, the skeletons outside Gadir in the Atlantis expansion, who mostly drop broken items even with my settings. So there are different weights for different creatures. Perhaps these settings are not weights, but multipliers for item weights in each creature file? Usually "Modifier" means it's a multiplier, just like the spawnMaxModifier setting is a multiplier for the spawnMax setting in each creature pool. That would mean that if a creature has an absurdly high weight for broken items then a multiplier of 375% would still outcompete the 1500% multiplier for normal items. But that still doesn't explain how champions can still drop broken items occasionally...

By the way, I noticed the creature files for the mermen outside Corinth in Loot Plus don't have the new textures. I guess they were added later? Those new mermen look radically different with Loot Plus and I only noticed because I had to test things without mods loaded. I don't suppose you just disliked their blue appearance and removed it intentionally. I fixed it so you can download and extract the fixed files from Loot Plus XMAX FTW when I upload the new version if you want. I also have a problem with the Sciron quest not starting, the questgiver NPC doesn't become available for dialogue after killing Porcus the Ketos. Dunno whose fault that is, yours or mine. I checked all related files and found nothing.

Okay, so it appears to have something to do with monster items. When I set brokenOnlyModifierCommon to -100, I almost only got broken items so it probably didn't accept the negative value and rolled over to its maximum value. Then I tried setting it to 1 while setting NoPrefixNoSuffix to 2000, and then this happened:

https://i.imgur.com/hX1tWT5.jpg

As you can see, every monster item is still broken, but the ordinary items are almost all fine. What's up with that?

I solved it. I increased the settings for yellow and white items by x100 (so 200000 for whites this time, 5000 for prefixOnly, etc) and this is what happened:

https://i.imgur.com/X02mPaN.png

The increase to yellow items worked, but not the increase to white items. That means it is indeed multipliers we are dealing with, and the original item weight for white items is no doubt set to 0 in the files of these particular mobs, so no matter what multiplier I apply to white items it will always be 0. Yellow items have some value other than 0 so the multipliers affect it. It's the only explanation. Perhaps this is something Loot Plus could fix? Make it so that all rarities for monster items use the default values for normal items or something like that, so that we can control them with multipliers in gameengine.dbr. It also gives better loot and you still don't have to touch gameengine.dbr yourself. It would be much appreciated. :P

I'll look closer into it later, but it's actually not the monster files these values are set, but loottable files. For example, item/loottables/head/commondynamic/helm_n01.dbr has values like "noPrefixNoSuffix 45; prefixOnly 4; suffixOnly 4; brokenOnly 100"
I haven't touched these files in my mod, but reducing white/broken drops with batch replacing wouldn't be too much work, I suppose.

Edit:
I'm not sure how defaultWeight is handled, or what the bellSlope does in effect, though.

Apparently all those /commondynamic/ loot tables are using reasonable values, the issue is the monster tables in e.g. /loottables/arms/monster/e_melinoe.dbr. I think those were the mobs I tested the settings on in the screenshots above, and in this particular file NoPrefixNoSuffix is not specified at all, might be an oversight. Can you batch insert the setting in all the files which it's missing from? I'd just give it one of the lower default values to play it safe in case it's inserted into a file that doesn't have it because it only drops magical items, in which case giving it a moderate value would make it detract less from the magical drops, or in case it's an ancient monster that's supposed to have old and broken items. And otherwise it can be adjusted in gameengine.dbr. I haven't learned how to batch insert, although I should probably look into it soon instead of editing everything manually with Notepad++...

Edit: Here are those fixed merfolk files for xpack2/creatures/monster/merfolk:
https://www.nexusmods.com/titanquestanniversaryedition/mods/19?tab=files
I tried uploading it to Mega but Steam removed the link.

I actually don't think the missing noPrefixNoSuffix is an oversight. As far as I remember, monsters have never dropped white variants of their specific non-MI items. I'm not sure what's the reasoning behind that, but it's always been that way.
The path to less clutter would probably reducing the equip chance for any of those items, while drastically lowering broken item weight (or delete it altogether), so the few item that they do drop are always at least yellow.

Anyway, apparently there's a new update v2.10 for TQ:AE in the pipeline, so I'll wait for any updates to LootPlus until that drops. And I remember explaining how to batch replace in the thread on the TQfans board (page 4 somewhere in the middle). I should mention though that I'm not a programmer in any shape or form, everything in this (and my other) mod is the result of trial and error.

New update? Oh god, what are they breaking this time...

Well thanks, I read that it's pretty easy to batch replace with Notepad++. Anyway, the mermen outside Corinth (as well as some other monsters) do drop white variants of their monster trash items. I'm not going to comment on whether it's all intentional, but I guess I can infer that adding the setting to all those files should at least work, it will recognize the setting. So I'll just get right to it. I'm gonna give them proper weapons and armor to make the trash in my merge a little harder.

It seems to work fine.

I replaced:
brokenOnly,60,

With:
brokenOnly,40,
noPrefixNoSuffix,20,

The weights get modified by the modifiers in gameengine.dbr of course which makes it harder to estimate what the result is, but I think these values should be fitting enough for most monsters. If you want to add it to Loot Plus, the files are available separately on the Nexus: https://www.nexusmods.com/titanquestanniversaryedition/mods/19?tab=files

Thank you for your help.

Edit: I should mention that these new settings will increase the drop rate of magical items since brokenOnly has a much higher multiplier in gameengine.dbr, so the 20 that's added to noPrefixNoSuffix does not make up for the 20 that's detracted from brokenOnly after it's been multiplied. brokenOnly has a default multiplier of +1200% for common enemies and noPrefixNoSuffix has a multiplier of +800%, which makes a combined weight of 780 for greys and whites before the change, and 700 after the change, so the weights for magical items will be that much more impactful. Roughly 10% more magical drops from the affected monsters, I suppose. But I think that's good because stronger monsters should give slightly better rewards.