Don't have much experience with guthooks beyond the one on my Buck Zipper, which I haven't used in years. I used a coarse ceramic rod to sharpen that one. One of the synthetic diamond 'sticks"should do it also.
There's a number of small sharpeners out there designed for serrated edges that could also be used. The DMT diafold Serrated Knife Sharpener, Model DMT01106 is listed as also being for guthooks. Never having used one, I can't say how well it works. Price is $25.00, so probably helps to have some knives with serrated edges that also need sharpening to cover that cost. I did a search using Guthook sharpeners as my search criteria and came up with others also.
