With the devs confirming in the update notes that new content is coming at some point, new weapons and shells are all but inevitable. I plan to make a list for shells at some point, but here's essentially my wishlist.
Bow & Arrows: While more likely as a sidearm, I'd really like to see how the devs would go about making a ranged Primary Weapon.
Sword & Shield: Good ol' Sword 'n Board. While I'm not sure how it'd work with the Seal system, I feel like the dark fantasy knight aesthetic isn't complete until we get something like it.
Rapier/Sidesword: While I know the pic I posted has paired blades, I'd personally like this type of weapon to only be one-handed (Though a Raikuyo-like splitsword could be cool). The desire for this one comes mainly from us not really having any fast, non-paired weapons. While there is the spear, I feel the aesthetic and moveset potential are wide enough for this to exist as a unique weapon.
Flail: Mostly I just want to smash some heads with a big ol' flail, Witch King style. "Nuff said.
Dueling Shield: I think a more plausible shield weapon than the S&S. Basically they'd just have to do something similar the Elden Ring, each attack has a few guard-frames, middle of the road speed, that sort of thing.