1) That is so small, I would just ignore it.
2) It is a tiny thing at the edge of the blade. That probably came from the edge of the blade hitting something as dingyibvs has allready said. If you hit the edge of the blade into something like the edge of the table, it is not really possible to stop things like that from happening.
3) Since it is at the edge of the blade and not where you contact the ball, you should not worry about that. You don't have to do anything. You could put a tiny bit of wood glue. Some have suggested super glue....it would serve the purpose as well. You could even just dab a bit of wood sealant on that area. But....IF YOU DID NOTHING, it still would be fine.
What blade is it: brand, model? I am just curious but it does not matter to the issue at hand.