I carry a small sharpener in my wallet all the time. Years ago, I took a Eze-Lap model L diamond hone, cut off most of the red plastic handle and it goes in the zipper part of the Eagle Creek tri fold wallet. Doesn't weigh hardly anything, but lets me touchup my knife anywhere, anytime. I'll use the back of my belt to give it a stropping afterward. The 600 grit medium hone puts a very nice cutting edge on a blade.
It's my personal belief that if you carry a knife, you should have something to touch up the blade. Modern compact diamond homes make that possible.