The problem with Arc is that it doesn't allow exporting data (history, bookmarks) to a file natively.
One way to do this is to use a script but that only exports Bookmarks and not the history.
I don't really use the bookmarks feature that much; what I really liked about Arc was that it was really easy to navigate to somewhere I already visited.
So, if you're like me, follow this guide and you'll be able to import your browsing history into Zen browser!