Hey there - there's a lot that still remains for combat; weapons, armor, and items are going to play a large role, skills will have more diverse effects, there's general balancing that needs to be done.
Mainly, right now, if you don't hit the enemy with heavy attacks early on to break their armor, you end up in a situation where you can't perform strong enough attacks to do anything to them, because as you get lower health and stamina, your effective strength lowers. The combat system is currently entirely deterministic (aside from what actions an enemy will take, which is a weighted random distribution based on how aggressive they are and the current situation), so there's no luck factor involved.
That may be an actual issue with the resolution - that should be working. When you change the resolution dropdown it doesn't resize your window at all? It should at least automatically resize each time you make a selection, and then it should save it when you leave that menu - we'll be adding a save button eventually.