If we're going to compare today's society to then, I'm going to jump up on a soap box here for a second if you'll indulge me. Violence affects people in very different ways. Being that my actual profession is the profession of arms, I know a lot of people directly affected by the violence associated with war. I have classmates from the Naval Academy who have been killed in Iraq and Afghanistan, and many friends and colleagues who have killed others in said places. Some are disturbed by what they do, some won't talk about it, others treat it like the job it is and have no qualms about killing the enemy in war, others enjoy what they do. It really comes down to the individual. I don't think the warrior mindset is all that different today than it was back then.
I think we paint the medieval era as a hyper-violent culture, but look around the world today, and tell me that we're not as violent. How many wars of all scales are being waged right now across the globe, from the Middle East, to Africa, to places no one cares to hear about. I would argue that we're more violent now as a race.
The difference is most of western civilization is removed directly from conflict. Those who serve do it away from home, so the only taste of war to most of society is the crap they see on the news. Trust me, those who serve are very aware of their mortality. I'm an instructor pilot now, and have already lost a former student of mine which has really put perspective on things for me. The major difference is the amount of people who directly deal with conflict. I'm not sure what percentage of the population in medieval times fought or were serving within their king's respective armies, but I'm willing to bet that a very high percentage of able bodied men were expected to take up arms when needed during feudal times and then later with standing armies. This lead to a majority of the population of a nation having experienced warfare first-hand or at least being greatly affected by it.
Now let's look at some statistics for modern times. In WW2, roughly 12% of the US population served in the military, in Vietnam roughly 4.5% of the population served. From 2001 to now, we've got a whopping 0.45% of the population serving in the military and taking personal responsibility for the defense of their nation. The 'problem' of dealing with violence has just been relegated to a tiny portion of society. I don't think the individual warrior is what's different, I think it's that there's just a lot less of them now.
oh, and on a lighter note, GO NAVY BEAT ARMY!!! (tomorrow's the army navy game)