I have always placed the core of Evil as Selfishness, that the self is the only thing that is important and anything that required to meet the needs of the self is acceptable.
The drive for advancement at any cost is a drive to fufill their own need for a position or place. While Good allows for competition as long as that competition is not to the level of destroying the others in the competition, Evil emphasises success at any cost.
Cruelty is a biproduct of Evil. An uncaring for the suffering of others to achieve their goal is a perfectly Evil function. Delight in cruelty inflicted upon others or self, is acceptable because it is simply a fufillment of their own needs, therefore acceptable.
Weakness is simply something that gets in the way of achieving ones own goals. Anything that stops you from achieving goals in yourself is a weakness and is simply not compatable with your needs. Some who are evil have issues with others who are weak because they could be strong and they don't understand why anyone would not want to be strong and able to achieve their own goals.
Discipline may or may not be an aspect of Evil. It depends on the goals of the Evil being. Many Evils are into satisfying their own needs immediately, while others plan and plot to achieve more stratigic needs. A degree of discipline might be acceptable, depending on the Evil beings needs.
Combat. Combat is a simple tool to achieve an end. If you like to show that you are superior (have a need that must be satisfied) you will engage in it freqeuntly, to prove you are superior. If you enjoy watching the weak squirm, combat is a great way to fufill that need. Combat is not Evil, it is just the easiest tool at their disposal.
This selfishness is the reason why Evil is Negative. Unlike Good which projects outward, giving to all, Evil draws thing in... absorbing everything in a point of self.
