He didn't only have a problem killing his victims in person; he was horrified by the violence in general, judging by his reaction to Prof. Burbage's death. He was horrified when he had to Crucio failing DEs.
Why do so many people insist on painting Draco Malfoy with the “evil” brush? Probably because no one likes to extend the “he was just a kid” excuse to Draco that gets passed around like a dutchie on the left-hand side to Harry Potter, Hermione Granger, and anyone else under the age of seventeen who does something rotten, as long as they don’t have a green S on the banner above their Hogwarts House. Right? That’s really what it boils down to, isn’t it? Draco Malfoy didn’t like Harry Potter, so we don’t like Draco Malfoy. And that’s what gives us internal permission to call Draco evil when the only thing he was really guilty of is stupidity. Let’s be real here. It’s not like Draco was trying to end the life of Katie Bell or Ron Weasley. They were accidental victims, kind of the way Harry Potter “accidentally” almost killed Draco. Draco didn’t wake up one day and say to himself, “I think the world needs to be rid of Professor Dumbledore.” Draco was ordered to do what even Lord Voldemort thought was the impossible — to destroy Professor Dumbledore. Voldemort didn’t really expect Draco to succeed; it was a no-win scenario Voldemort was going to use to end Draco’s life as Lucius Malfoy’s punishment for losing Tom Riddle’s Diary and failing to obtain Sybill Trelawney’s First Prophecy. Draco only took on the task because he wanted to put his family back in good graces with Voldemort — really, to save his father, more than anything. We can say Draco was misguided and jaded by his family’s Pure Blooded beliefs, but Draco was no killer. We can even say he was a coward. But evil? Mmmm… an evil Draco Malfoy wouldn’t have kept his mouth shut when he had the chance to hang Harry, Hermione, and Ron out to dry at Malfoy Manor. Nor would he have so clearly rejected the traditional Malfoy bigotry when he married Astoria Greengrass. See, there’s this thing no one here in the fandom ever wants to credit any character for doing in the Harry Potter story — realizing they made a mistake. Changing their minds. Having a change of heart. We prefer to just keep despising someone. How junior high school-ish of us. There’s a word for people who can’t accept that other human beings make these things called mistakes. The word is, “hypocrite.” Let’s remember that word the next time we want to vent bitterness and hatred on someone who realized they made a mistake and try to make amends for it. In fact, I take back what I said about Draco being a coward. And Draco was clearly not at all evil. Maybe we should stop holding every person's feet to the fire because they make the mistake of following the guidance of their parents and for not being perfectly nice to Harry Potter every step of the way. Really, Harry could be as big a putz as Draco was at any given point. Hermione too, while we’re on the subject.