Here is what I recommend for cleaning and adding sealant and conditioner. I like Montana Pitch Blend, Obenauf's and Skidmores.
TO CLEAN:
Fill a bowl with warm (not hot) water and remove any obvious dirt from the sheath with a clean boot brush.
Wet and ring out a soft clean towel. Drizzle a small amount of MPB Leather Oil Soap onto a wet, clean, soft cotton towel. (If you do not have Leather Oil Soap - simply use a small amount of Dawn dish soap in your water the bowl in step 1)
Swirl towel with soap directly onto the leather to lather as you work gently into skin.
Rinse towel and ring out any excess water. Return to the leather to rinse and dilute remaining soapy water.
With a second clean, lint-free cloth, wipe leather and wick up any excess liquid.
Place sheath on towel and allow to dry in room temperature. Do not apply heat to speed drying.
TO OIL / PROTECT:
If your sheath is not dirty and you simply want to oil your sheath (every six months) please skip the cleaning process. If you have just cleaned your sheath and want to reapply protectant to the sheath you can use MPB Leather Oil and Conditioner (liquid) or Dressing (soft paste wax).
Add a small amount of Leather Oil or Dressing into the palm of your hand then massage directly into leather. (If you are using Leather Oil - less is more - be careful not to over-oil)
Apply a thin, even coat (no need to over-apply)
Allow to dry over night
Finish by buffing briskly with a clean, dry, lint-free cloth or boot brush to help even out your application and remove any excess oil. (This step is important as excess oil or dressing will attract dirt.)