Place it in front of anything dangerous. It's as simple as that.
Super Sharp Sword 5 Points
Swing it towards your foe. Haven't won yet? Repeat previous step.
God Mode On 50 Points
Finished the game without dying even once and cheating.
Supporter 5 Points
So the demo impressed you so much that you visited the store page and added the full game to your wishlist or maybe even bought it. At least I hope so. Who am I kidding? You just wanted that achievement, didn't you?