Making separate collections for standalones and replaces would be a lot better.

Since Iggy used spear for high jump I guess V's cane as a spear would work?

nice, now the only thing that grinds my gears is how Rebellion is stronger than both Sparda and Dante, otherwise it's great

Yeah, they work together but my advice is to use as little standalone as possible, so for example:
- Red Queen Skin on Sword
- Rebellion Skin on Large Sword
- Devil Sword Sparda as Standalone OR Devil Sword Dante as Standalone

this way you have all these swords visually but no bugs at all

So does the skin works together with the standalone?Like I use the red queen skin and using the default engine sword but also have the standalone as stronger version I'll use later

you did nothing wrong, sadly that's a bug of the game, even if it allows you to have multiple standalone weapons, sometimes it gets buggy and mixes models.. if you check them in the equip menu they all work, while outside of it they do not.. that's why I created also the skins, so you can have some of them as skins and only some others as standalone.

I got an issue with the swords, I have all of the standalone weapons subbed and activated, but when I equipped Gladio(Dante) with devil sword sparda, Noctis' Red Queen appears as Sparda in combat, the same happened when I deactivated Sparda and have Gladio use Rebellion instead, the Rebellion appears as Red Queen. Anything I did wrong?

Just subscribe to them and you'll find them in the inventory to equip!

how do i use this in the game? first time using the workshop

is there devil sword sparda but for sword?