My DS1 and 2 are 3.5 and have a few good friends who they play with a lot in the park before and after preschool. I am friends with their parents too. Most days, two children in particular turn up with sticks that they proceed to run around and play fight with (until I take them away like the total spoilsport I am!).
I remember when I was little, a child being blinded by a stick and it has stuck with me ever since. Losing a eye is a terrible thing but most parents seem a bit blasé about the issue or else it just hasn't occurred to them that it could happen.
Maybe I'm being a bit paranoid? I don't let mine play with sticks and I don't want them being put at risk by others doing so as well.