A2 steel is a little more difficult to sharpen but retains its edge for longer. The downside being, because of the different grain structure the A2 won’t be quite as sharp as the O1. What does this mean in practice? If you’re roughing something to size or planing abrasive exotics then A2 is probably the better choice. Blades are available with 25° or 50° bevels in A2 steel.