To make a fist, hold grab first, don't press trigger. The game does not check that - but maybe I should change it, so if you use your fists, you do more damage. BTW killing an enemy with melee gives you some energy for weapons.
By "energy points" do you mean just energy management or how to get energy?
Things are going to be explained in the game but not yet - as some of them may still change - and right now I want to focus on finishing the gameplay loop and then iterate.