Quoting Watashi (view post)
I bought the scythe because it looked cool but honestly I ended up never using it. It's not nearly as powerful as the sword, and later on you'll get secondary items/weapons that will push it to the back of your list of priorities.
Just buy any and all sword moves that you can. There are two moves that go really well together and I max'd those out first - the first is where you uppercut the enemy into the air with your sword, and the second is when you hold the attack button for a second and you do this giant jumping spin attack where you drill them back down into the ground and hit them like 10 times.
Also, there's a dash move that's great, where you thrust your sword forward and spear them with it. It's very strong.