You can use knives to instant kill enemies that you have like toppled over in a certain way. You can also use them and I've just started really utilizing this and it has changed the game for me. There's a parry that you can do now, which is great because most enemies are using axes or scythes or pitchforks. And with the tap of a button in exchange for a little bit of durability of that weapon, you can block the attack. The very first time you get to a shop, you can upgrade all your weapons right at the top.