If you can find one, the now discontinued Byrd Duckfoot diamond sharpener does a great job on serrations. Easier to find is a DMT Diafold serration sharpener. It is a tapered rod that at some point on its length will match most scallops. Just remember, serrations are chisel ground, i.e. all the bevel is on one side of the blade, so you need to hold the blade higher than you normally would on the bevel side to match the existing angle and flat or nearly so on the other side. It's pretty easy to scratch up your blade doing it, so if that sort of thing bothers you, work very slowly and carefully. I recently acquired a serrated Spartan that needed some attention, and the Duckfoot made short work of it.
If you can find one, the now discontinued Byrd Duckfoot diamond sharpener does a great job on serrations. Easier to find is a DMT Diafold serration sharpener. It is a tapered rod that at some point on its length will match most scallops. Just remember, serrations are chisel ground, i.e. all the bevel is on one side of the blade, so you need to hold the blade higher than you normally would on the bevel side to match the existing angle and flat or nearly so on the other side. It's pretty easy to scratch up your blade doing it, so if that sort of thing bothers you, work very slowly and carefully. I recently acquired a serrated Spartan that needed some attention, and the Duckfoot made short work of it.