Disclaimer:
This is a set of ideas related in a unique theme - the creation of different statuses that lower resistances to status effects and damage types.

A. Motivation:
Why? I find myself a bit perplexed at the situation that we find ourselves in the game: We can protect ourselves 100% to some status effects and avoid being inflicted with combos like Fire+Poison in a Danger Mission, or play in Lockdown and pass through Shivermist Busters like they were scenario decorations, or equip Ancient Set and be given a hit by wheel traps in FSC to receive ONE bar of damage, with NO Unique Variants whatsoever.
Also, when I use a status effect bomb, I see that the effects wear off quite fast. Not frustratingly fast, but it is enough so that we have to be spamming area effects to keep them on the enemies. Or, if I use Polaris or any other status inflicting weapon, I keep shooting at the enemy because I know the Shock status effect won't kill off the enemy - I might as well use non-status effect weaponry, though Polaris counterpart is Normal damage. See? I use Polaris because of the Elemental damage type, not the Shock status effect that comes with it, even if in Lockdown it may help a bit.
So, I would like to be able to create a way for "status lover" people to be able to inflict debuffs in this game in a way that it may be called "effective".
To be able to reach this, I propose working around the defense values against damage types and status effects that we already have, attacks, traps and weaponry that would reduce a set time these values.

B. Different statuses, for different values:
I suggest to create a set of status effects that reduce the defense value against a specified damage type or status effect. With that, I mean a "reduce resistance to Shock", a "reduce resistance to Piercing type", etc.
They should take 10 to 30 seconds to wear off, depending on Tier most likely, though different ways to inflict these may give shorter times - Vials, for example.
While inflicted with a "reduce resistance to X" effect, the enemy or player character has a "Maximum!" negative status effect added to himself. Moreso, player characters get it in both Helm and Armor equip, effectively being able to nullify Unique Variants.
Maybe also make the related status effect inflicted automatically of the "Very High" type while these status are up, but maybe this would be too much.

C. Everything must have a theme, here is what I suggest:
There are ways to reduce resistances to illness in real life - exposition to heat, cold, stress. I think that in game like this, the victim should be "covered" whole in the resistance reducing element. For this, I suggest:
- For status defense reduction effects, I shall center on a "gel" based theme.
- For damage type reduction effects, I shall center on a "wave" based theme.
Gels are able to conduct better things, and I put them here for status effects - Fire should have fuel type triggers, Shock should have saltwater and such triggers, Freeze could have liquid nitrogen triggers, etc. Visual effect may have the enemy exchanging palette to a color that represents the status that he got weakened to: Orange red for Fire, green for Shock, blue for Freeze, etc.
Waves are able to go through everything, so maybe we could have different wave like triggers to reduce damage type defenses. Visual effect may have the enemy get around himself a weak static wave with the color of each damage type - red, yellow, green and purple, representing Normal, Piercing, Elemental and Shadow.

D. How we may inflict resistance reducing effects:
1. Vials:
> Fuel Vial: A canister filled with an old energy source. It is really flamable!
This may be an example. You throw the vial, and the enemy gets splashed, palette exchanging to orange red. If it was a player same deal, and the player would see the icon representing "reduced resistance to Fire" status.
These Vials, like status healing caps, only have one grade and set time.
Damage type defense reduction Vials may need to have a different "name" as "waves" can't be technically be contained in a bottle... maybe "Orbs"?
2. Bombs:
- For status resistance reduction: I thought that a possible set of bomb weaponry could have "Snap" like bombs - you know, the 1* bombs that damage and inflict status, only that these would explode in a liquid gel sphere and inflict the debuff 100% for sure. Damage of course would be subpar when blasting, but these bombs are made to be used with Haze bombs and other status inflicting weaponry. Progressing in the Alchemy tree would give bigger gel domes and more damage, but still not comparable at all damage wise.
- For damage type defense reduction: These could be an antenna shaped bomb that would blast a strong wave when bursting. Shadow themed ones could have totem shaped bombs for that end, being mostly "mystical" monsters. Same as the "gel bombs", the "radio bombs" wouldn't damage a lot, but inflict the debuff always.
3. Guns:
I think that if we want to "cover" an enemy in the gel or wave, cannons that would throw "paintbombs" - filled with fuel etc - and wave cannons that would throw shockwaves could do the trick. These weapons are almost suited for this role even better than bombs due to its selective nature, though maybe for balancing purposes it would be wise that they wouldn't inflict always the status effect, unless they had a slow speed or few bullets per recharge.
4. Why not Swords:
I don't think Swords are suited for this purpose, I know we have a "poisoned sword" - Vile Striker, but both gel and wave, the themes I think suit the defense debuffs, wouldn't be able to be applied here. The only exception? The Spur line - it throws waves. It may work to have a X% chance to inflict status/damage type defense debuff Spur Alchemy tree, but the rest of the swords wouldn't fit. Even more so, it would actually give the debuff role to the other two (arguably neglected) weapon types if this wasn't made.
5. Gel cubes - Structure:
I think that a new "cube" structure that we may encounter in the Clockworks may be these: instead of explosive blast cubes, ones filled with gel, translucent and with the color and reducing status effect related with the level. This way we may blast a Fuel Cube in a fire strata level. The problem here would be that not many enemies are able to be inflicted with a status effect related to its strata, though I also share this idea as there are some exceptions.

E. How enemies may make our lifes harder with this:
With this system, Clockworks could get deadlier than ever. Here are some things I propose that could be made to buff difficulty by implementing the system:
1. Totems: Their waves may inflict the "damage type defense reduction: shadow" effect. Now Zombies may be deadlier!
2. Gremlin Knockers: Adding types that instead of inflicting status effects/damage inflict debuffs/damage.
3. Gremlin Scorchers: They throw oil around sometimes, maybe they could also spill fuel around as a "circle attack" to inflict with "status resistance reduction: fire".
4. Gremlin Mortafires: Their rockets are now filled sometimes with fuel to inflict "status resistance reduction: fire". Making C42 more dangerous.
5. Wolvers: Do you know that bark they sometimes make? It could be a circle AoE wave that inflicts "damage type defense reduction: piercing", though no damage.
6. Snarbolax: His menacing howl would inflict around half screen range "damage type defense reduction: piercing", of course no damage though.
7. Status Chromalisks: Their goo attacks may inflict BOTH statuses and "status resistance reduction".
8. Gun Puppies and Howlitzers: They could have new attack - a frontal bark when approached, able to be blocked, that may do a bit of Elemental damage and inflict "damage type reduction: elemental". Howlitzers' one reducts Shadow defense.
10. Oilers and Nuclear Oilers: When damaging, they may inflict "status resistance reduction: fire" - and in Nuclear Oilers' scenario, also poison status resistance reduction.
Not only this, but maybe we could have new traps designed in the Clockworks, like:
- Wave mines: A semihidden mine, able to be seen thanks to its antenna planted in the ground. They would come out, and blast a wave selfdestructing themselves, similar to the Radio Bomb I suggested up there. They would reduce damage type defense, but inflict very small damage.
- Gel dropping tubes: Sometimes, you may need to traverse an area with shower like shaped tubes that may drop gel types at set time intervals. They wouldn't do much damage, but reduce your status resistance.

E. How Lockdown could get more interesting:
As well as already with this suggested status improvement system, making status weapons more dangerous, the Gel Cubes I suggested before may actually be useful here if some respawnable ones would be set at strategic points, or have "Mega" Gel Cubes that would spread gels like a 5* Gel Bomb. Also, like the Snowballs in the winter scenario, there could be "Gel Spheres" with the Water Orb look that may reduce status effects.
About the "wave" defense type reduction, this may require new structures. Though Capture Points maybe could blast a wave every now and then, giving people who actually capture points an advantage.

F. Show is over: This is it, I hope you like it. If not, it is ok too, I enjoy writing these : ) Though I think this would make the game much more interesting, both PvP and PvE wise, even more so if enemies can get this too. Until next wall of text!