After creating a full list of most sets + effects (base values) i started being creative with Set mixing. (using the magatana ofc)
Id take 4 Piece Bonus from the Red Demon set (Spearfall + 20%, Close Combat +9.1%, ATK/DEF +10). That would be Spear and 2 armor pieces. Leaving me with 1 weapon and 3 armor pieces.
So we can fill another 5 set bonus. Could use Warrior of the West. adds more close combat damage (around the same) and the much easier to apply Lightning Debuff. Honestly Fire element sucks because ALOT of enemies are resistant (or immune) towards it and it generally stacks much slower than other debuffs.
That would be something like 18%~ Closed Combat damage and 30%ish DMG on electrified. Heavier, but more effective. If You actually use the Spear from the demon set, or Sword from the "West" set, you can fill one Armor slot with any set of your choice (best would be Red devotion DLC for 16% Final Blow, but Crossed Sickle gives 15% for those who dont have it)
The problem with other combinations is that, while they make look better on paper, they are incredibly heavy and therefore not ideal for the majority of players.
For example, i was thinking of this combo: (playing with dual swords, since OP) "A master swordsman" 4 set, 1 weapon, 2 armor = 10.2% CC DMG, 30% Sign of Cross DMG(duals iai strike), 12% Skill ki redux (great for the iai and kick spam, the bread of and butter)
Leaving us with 3 armor slots and weapon slots, i think that "Crossed Sickle" set fits perfectly of course. 5 Piece set. 1 Katana + 3 armor pieces and boom you got another 15% Final blow, 20% behind and 7.1% CC DMG modifier. But both sets are extremely heavy.
Red Demon 5 set + Sickle 2 set + Red devotion 2 set can also work and is much lighter. You are still limiting yourself to fire debuff, but you still gain 30% final blow dmg at minimum weight usage. Red demon + master swordsman can also work, but heavier again. Up to your prefence really. From what ive seen final blow and from behind modifiers seem to make a much bigger impact on the final damage though (if you actually land them ofc).
Edit: Also i think that if you destroy most content anyway ( depending on play style), its much better to stack raw damage, than silly debuff damage. If you use any of the following methods, it doesnt matter anyway: Sloth, weakning, carnage. If you are using a +10 320 weapon, content is trivialized anyway. Same as using knockdown cheese with guardian spirit talismans.
Better to stack raw damage in those instances. (Behind damage / Close combat damage, Final blow, etc)
What do you guys think? Discuss! 🙂