I just rewatched 'Soul Eater' and that got me hunting for shows with that same vibe of weapons being characters, you know? 'Noragami' is probably the closest parallel I can think of. It's less gothic school and more urban god lore, but the idea of divine weapons—called Regalia—who are human spirits bound to a god is such a cool spin. They have personalities, they bicker, and their power depends on the bond with their master. Yato and Yukine's whole arc is basically about forging that relationship.
Then there's 'Kill la Kill' from the same studio. It's way more over-the-top and chaotic, but the sentient sailor uniform, Senketsu, is absolutely a weapon partner. The dynamic between Ryuko and Senketsu is central, with the uniform talking back and evolving. The power is literally woven into the clothing, which is a bizarre and fantastic take. It lacks the 'partner' collectathon feel of 'Soul Eater', but the core of a living weapon symbiosis is totally there.
For something a bit older, 'Darker than Black' doesn't have talking weapons, but the contractors use incredibly unique and personalized abilities that feel like extensions of themselves, often with heavy personal costs. It's a colder, more spy-thriller version of unique power systems.
Honestly, finding the exact combo of gothic aesthetic, school setting, and weapon-person partnerships is tough. 'Soul Eater' really carved out its own niche.