For my internship I stayed five months in Curacao, a week on Aruba and a few days in Bonaire. Believe me, Aruba is a safe place to stay especially for a holiday in and around the hotels. I’m Dutch and the locals where very friendly to me. I can’t tell you for shore, but I think they don't deal non-Dutch-speaking tourists differed.
Off course there is happened a few things that might make you think it’s a dangerous place, I mean the tragedy of the disappearance of the US girl. Remember it’s still a Latin-American country, some very poor people and drugs problems. But just like any other county go around the problem zones and if someone gives you an advice of not going somewhere, don’t go there!
I cant help you about the knife laws, I know it isn’t really firm aslong as you not go to a bar whit a Ka-Bar. Here’s my advice: As I remember there isn’t a lot of outdoor/nature so you don’t need a fixed knife. So bring a small folder, Swiss-knife or leatherman it will be enough for small outdoor and everyday carry. If you are going for diving bring a midsize dive knife. Just put it in you dive gear if you are traveling to a dive location. NOT as hand luggage in the airplane off course.