You don’t have to separate the links with anything. They’re already in an unordered list. If you want to separate them, you could use CSS to add a graphical list bullet that would act as a separator or you could add a left or right border – again using CSS.
I managed to figure out by simply looking up the ‘wp_list_pages’ in the codex, there I was able to find that there is in fact a parameter that can be passed called ‘link_after’, which does what I want. So to display a / character after each link I would simply just pass the parameter like this:
You’ll of course have a / after every link including the last.. if that works with what you have fine, else you’d just need to return the data and do a little PHP magic to not show the / when printing the last item.