Amals, I always have an EZE-LAP Model M diamond rod with me. It has never let me down yet. Many consider it to be one of the MUST HAVES for knife maintenance out in the field. AT SOME POINT I plan on getting some nice leather for my forthcoming BullDog and for my Wardog. I had thought of a piggyback but then though that the larger blade (BullDog or larger) should probably be on it's own belt, and I have a L O N G nylon belt that will serve well as a baldric.
HOPEFULLY my large knife will soon be the 911! I have a DF but it is heavy and is I think actually more knife than I need. Don't plan on making many log cabins with a knife!