I'm not in sync with the majority of MDC on this particular topic. I have no issue with weapons play, aggressive play, rough-housing, etc. (as long as all parties are okay with it - "stop" means STOP). I let my kids watch screen violence that's not age appropriate, and my guideline for that is the child's comfort level. For ds1, that was pretty far out there. DD1 and ds2 have both seen all three of the original Star Wars movies, and all three LOTR movies. They're okay with that.
DS1 - almost 17 - is really into Spider-Man and has been since he was about 3 or 4. He also loved Power Rangers in their heyday. X-Men (cartoon). He goes and sees all the Marvel movies, and used to talk about ecoming a professional comic book illustrator (he probably could). He has a whole collection of plastic toy weapons (mostly swords, but also some battleaxes, knives and pitchforks) that has been growing since he was about 3 or 4, as well. He loves swords, especially. As a kid, many of his games involved being a ninja, a pirate, a knight, etc. and killing people.
I've been hearing aobut how kind, pleasant and respectful ds1 is since he was a kid. I hear it from teachers. I hear it from his friend's parents. I heard it from a parent who shared his cabin at Cub Camp. He's creative, imaginative, artistic, and mostly very gentle. He has three younger siblings, who climb on him, pester him, and occasionally hit him (ds2 has some impulse and aggression issues). The most I've ever seen him do is snap at them a little bit. He adores his little sister, and is a big fan of "cute" (stuffed animals, baby animals, babies, cute cartoon characters, whatever). He's had three steady girlfriends, one of whom lasted about a year, and has never crossed any lines with any of them, in terms of respecting their boundaries. He's still good friends with two of them. His only violent altercation in his life ended when he told the guy who jumped him to, "chill, dude - you don't wanna do this - go home and cool off", while blocking fists. (The guy in question had been going out with ds1's girlfriend and blamed ds1 for the breakup, and jumped him for "stealing [my] girlfriend". They were friends before and after.)
What I'm saying is that ds1 is the farthest thing from violent. It's just not the way he does things. He's pretty diplomatic, likes to smooth things over, and wants people to get along. He's been watching out for kids smaller and/or physically weaker than himself ever since he was old enough to understand that kids could be smaller or weaker. He still loves swords, wants to go back to Tae Kwon Do and watches movies that would make me puke.