Wheter you are a sesoned ultralighter or simply don't want to carry heavy gear when out hiking, having a sharp knife is still a good idea.
This ultralight diamond knife sharpener is a good way of making that happen without logging around on a classic whetstone.
Two sizes are available and both of them can be had in two grit variants:
Fine/Coarse (600/300 grit) or Superfine/Fine (1200/600 grit)
For most people we'd recommend the Fine/Coarse