tidal kiln
Make a mastery system for the different weapons that unlocks skills everyone can get no matter the breathing style/demon art. (somewhat inspired by demonfall)
Some ideas for the skills -
Katanas:
1st skill - Unsheathe skill: something like heavenly strike from GOT, you put your sword back in the sheathe and unleash an unblockable strike
2nd skill - Dash skill: dash behind your opponent and hit him (blockable if you turn around fast enough, frees you from a stun combo)
3rd skill - 3 strikes skill: unleash 3 strikes really fast, doesn't interrupt your combo
These are some ideas just for the katanas, I'm not sure what kind of system would be implemented the best for that. Could be levels, could be a skill tree or something else. I saw a suggestion about passives too (like bleed on wind breathing, etc.) and it would be great with that
I'm not sure if there are other weapons either, but here are some for gyomei's chains too:
1st skill: Mace bash - hits the mace in the ground, knockbacks a little and frees you from a stun combo
2nd skill: Spinning strike - stars spinning the chains, the player becomes slow but blocks all attacks while doing damage for 1.5/2 seconds
I'm aware that this will probably be a lot of work and might not be perfect but still it can be a great feature.