I don’t know if this is a bug or a feature but I found this video online using a greatsword and rapier combination to give passive buffs from one to another …
https://www.youtube.com/watch?v=2LDKRW252UQ&ab_channel=bianca
The Bug/Feature can be done by respec of the skill you don’t use to the skill that you want to use, so for example you can respec all ur points in greatsword with ur greatsword sheathed then press the other weapon key and it applys all the passive buffs to the other weapon…