Sorry I have read more of the thread and seen this.
A general pattern of wanting to be in control, of being somewhat socially domineering, and lashing out sometimes to the point of aggression or violence is not really a pattern associated with a lack of conscience. In fact it's more associated with anxiety, or difficulty with emotional regulation or cognitive flexibility. Aggression in general can just be immature behaviour, rather than a baked-in personality trait he will always have (though I do agree it's important to take violent behaviour very seriously).
Does he tend to feel remorseful after something has happened? Or in any situation at all (e.g. would he feel remorseful if he hurt someone or broke something belonging to others accidentally, even if not when he did that deliberately?) Does his own behaviour scare him, is he upset? (Again: ever? Some of the time?) Does he understand that his response is extreme, or does it feel normal/justified to him? Is he appropriately frightened or worried by things like blood/injury or witnessing violence/aggression from others?
From my understanding (I am not an expert but I am interested in behaviour) a child who doesn't have much in the way of conscience/empathy would generally not feel remorse about any actions which hurt others, whether purposeful or accidental, and would not see their own behaviour as extreme. They are generally not upset about what has happened, would consider it a reasonable choice of action, might be surprised or annoyed that adults are upset by it, and will only be upset about consequences to themselves. Sometimes they also have a fascination or curiosity about things like injuries which most children would find frightening.
Children with the most worrying behaviour profile seem to gain pleasure from violence, and may have history of harming animals or insects on purpose. They generally don't care at all about being punished and won't be upset even if you do punish them. They tend to have an extremely strong and persistent desire for revenge. This is extremely difficult to work with, basically only reward works. Punishment doesn't work at all (probably because they don't care about social disapproval).
Both of those profiles, especially the latter, are very rare. The first can sometimes be seen in autism, and can also sometimes be indicative of more of a mismatch where the cognitive/logical intelligence is much further ahead than the emotional intelligence, ie they may grow out of it and do develop more empathy as they get older, and you can use behavioural strategies in the meantime to shift the motivation profile of violence, and sometimes reasoning and some social skills training to try to help them recognise emotions in others which can help with the development of empathy. Some adults do not ever develop much empathy and can be considered sociopaths, but it doesn't mean that they are all violent/psychopaths. They can be perfectly law abiding especially if they see benefits from staying on the right side of the law - so if you suspect this (and again, it's unlikely) focusing on ways that he can gain social status and power in a healthy way are usually very positive, so that a loss of social standing or e.g. ability to take part in sports, make money etc can be balanced against this in order to discourage violence and other ASB.
OTOH the most common presentation, where children are acting in a controlling manner (sometimes escalating to aggression/violence) in response to anxiety, or difficulty coping when someone's behaviour is unpredictable or difficulty handling their own emotions (e.g. struggling with losing or frustration, getting much more easily wound up than other children, etc) tend to either feel somewhat distressed after they have been violent, or they feel righteous/aggrieved. Either way, they tend to say things like "But I had to do that because otherwise he wouldn't stop saying that!!!" - they tend to feel that it was the only possible/logical choice and that their actions were justified in some way, but they are also aware that it's not an ideal or first choice type response, and they wouldn't choose it if they had a better option - they tend to feel as though they were backed into a corner and had no choice, although often from an adult perspective it does look as though they had blinkers on and didn't stop to consider any other options (which is because IME they haven't).
They often feel that their actions were in proportion to what happened, which is more of a reflection that their perception of what happened was inflated compared with anybody else's impression of it. Or they recognise that they were not in proportion but basically they either just went past the point of being in control, or they didn't know what else to do, or they didn't stop to think and they just reacted.
I'm not going to say this is easy to handle, because it's not, but it's much more straightforward than a scenario where a child is actually lacking a conscience. What children need in this scenario is skills, basically. They are lacking skills either in self-regulation, which is about recognising that you're getting wound up and choosing to step away and do something else instead (and knowing what to do instead) or response inhibition (impulse control) ie stopping and actually considering the consequences of their actions, flexibility which is about understanding that other people are individuals and you can't always control them and shouldn't try to, or distress tolerance, which is more about being able to coach yourself through feelings like anxiety, frustration, upset etc without it coming out at other people.