As long as the blades are steel then they can be sharpened, I would think a high carbon grade would be the minimum to use on any blade you want longevity from when buying from an army surplus or other stores that sell imitations, most of the imitations wont have a blood edge and scalloping, Ebay will only be Chinese copies so no guarantees on the quality and if you use them it's likely the handle will fall off
Don't expect it to last like a genuine sword would though, I've no idea what grade steel they use but it's folded over a hundred times and is much harder than any other blade or steel I've ever seen.
My crappy photo doesn't show up the scalloping pattern on the blade edge either which looks awesome when it's right in front of you.
