Having twin sword could be a fun weapon. Maybe it could be a faster, three hit combo type weapon, when you press the attack button consecutively. To compensate for being a faster weapon, it could be slightly weaker, to balance the game.
Also a katana could be fun as a weapon, basing it around a parry system like Sekiro. If you time the parry button correctly just before the enemy hits you, it could knocked back enemy attacks, leaving them open for hits.