Gunpla accessory packs are not all created equal. For example, many of the Iron Blooded Orphans Arms are engineered to work with very specific models. Try and use them with another IBO kit - or worse yet, a non IBO model - and you may not get the results you want.
On the other hand, the packs that were made as part of the High Grade Build Fighters line were meant to be more generic. The boxes show the accessories being used on all sorts of non-Build Fighters models, likely to encourage you to go wild and experiment.
Anyway, I’m assuming the same thing is true of the accessory packs made for Gundam Build Divers, which is why I picked up this Marsfour weapon set way back in December:
Simply put, it’s a pack of swords. I figured I’d be able to re-use them with any kit that happened to look good carrying melee weapons. Unfortunately, I never got around to cracking it open and painting them, so they sat on the backlog.