One of many options is to:
clean khuk
---My current preference is for SoftScrub Orange;
----I don't know if it has any significant amount of limonene
---Make your own similar by mixing citrus solvent (GooGone Pro)
----or any cleanser with mostly citrus/limonene with a mild
----abrasive like calcium carbonate, baking soda, or similar.
-----Both BonAmi & SoftScrub are calcium carbonate.
-----If the citrus cleanser makes a persistant foam when you shake the
------bottle then it has surfactants & water in addition to limonene.
dry khuk
---air dry overnight, or fan dry, or oven dry after warming
----on Minimum temp first, then turn Off oven and place khuk in.
----OR; wipe down 90+% alcohol, then acetone/nail polish remover.
wax khuk
---Rennaissance Wax is used by museums & considered archival quality.
----Its a microcrystaline wax suspended in a volitile petroleum base.
-----Last time I had it out I thought it smelled like kerosene.
---Any wipeable wax should work on a user khuk,
----longterm storage requires the most care of course.
sheath khuk
---Make sure sheath is dry, & has no debris or anything absorbed
----that might promote rust.