Do you think some other series should try the "weapon partner" gimmick again or is that just too connected to soul eater to work? (even though I now that soul eater wasnt even really the first to come up with it)
I think someone else can pull it off--I don't think it's connection to Soul Eater would stop that.
In fact, it would help: "If you like the power system in Soul Eater, you'd love this series."
Sometimes this works better when tone, setting, and theme are different: Noragami is a pretty good companion piece to Soul Eater. But whereas Soul Eater as a series was about themes such as friendship and courage, Noragami is far more about memory, the past, definitions of humanity, religion, belief, and whether you can ever transcend your nature, your creation--in other words, whether you can transform.
Or, you know, the weapon gimmick was already done in Transformers. Megatron turns into a gun, someone else wields him. Tsubaki Nakatsukasa is basically a triple-changer. Make her into an action figure--there have to be fans who would buy that.
But I think the weapon partner gimmick would need to do a lot more to get out of the shadow of Soul Eater. It would need to differentiate itself, perhaps not only by genre but even medium.
For example, what if you had a video game that was, "Soul Eater, but a video game." A fighting game, but how well the fighter works depends on which partner they are paired up with during the character select screen. Maybe you unlock new weapon partners in combat, maybe there is a story mode where you meet new characters and partner up with them as your weapon. Maybe some weapons are forced onto you and end up being a bigger hindrance in certain stages or fights depending on which fighter you main, so who you main as your primary fighter can make it easier or harder to use certain weapons (think about how Black Star couldn't wield Soul, so he would be a specialized fighter, but Kilik could wield the Pots, the Thompsons, and Azusa, so he'd be a more well-rounded fighter to choose for beginners).
