Something is wrong with a power sword which i’m equipping. This cannot be replaced. Whether you change it to a dagger or an axe in your backpack，In the game, you’re still using the BUG power sword.
Check if you have one curio equipped more than one time. I had the same issue and for me it was because i had the same curio in two slots (don’t ask me how that happened). When I correctly got equipped three different curios, weapon switch worked again.