I've seen a post by Greg Gutcher where he recommends Chelsea Leather Food or Picards for the sheaths.
I don't remember which forum I copied and pasted it from or if it applies to leather grips too though.
If you need protection for the leather because you actually use your knife then use Obenaufs. If you want a wall hanger than Ren Wax is fine.
Ren Wax, if needed.