Rust along the edge can be a problem. If it is deep you may end up with jagged bits on the edge that will give you a scratchy shave. As long as they hone out, they could be used as is. If you dont want to get overly extensive you could use a utility knife or single edge razor and scrape the worst of the rust off. The bubbly bits will be deeper than just surface rust. You will have some pitting in those locations. Problem with rust on a hollow grind is that there is not much material there to start with. To completely remove the rust/pits you have to remove steel which could leave your blade too thin and flex or worse yet, sand through the steel and end up with holes. Scraping it clean then hand polishing with something like MAAS will clean them up a bit, Then hone and use.