Examine the crack in the blade. Check to see how well the pieces fit together. Always check the blade after use because small cracks are much easier to repair than large cracks.
Sand off the rough or sharp edges of the crack. Once the crack is smooth, press the edges together to check for fit. Apply an epoxy resin glue and filler to the crack. This glue is sometimes referred to as an araldite. Read the product description carefully to be sure that it is meant for the type of crack you're sealing.
Hold the crack closed and let the epoxy set. Once the epoxy has dried, reinforce the sealed crack with athletic tape. The taping isn't necessary, but it can provide a pad for the repair, and help stop the crack from reforming.