Craig:
The dye used on the sheaths is built up and not polished, so it has a dull surface. If you use any preparation that softens leather (mink oil, neatsfoot, etc.,) be careful not to apply so much that the leather stretches and sags on the wood.
I scrub mine down with a section of T-Shirt (man's most valuable tool, next to the blade
) wetted with Lexol. This helps the dried leather, and scrubs off the excess dye. IF a section cleans off down to the "brown", I touch it up with Kelly's or Fiebing's leather dye (not polish - these are Milwaukee's second-most useable liquid products). I wait about a week, until the moisture in the wood has had a chance to stabilize from all its travels, and then re-finish the leather.
After Lexol/dye treatment, rub the whole rig down with a dry cloth to remove excess dye (there is ALWAYS some excess) and wax it with Kiwi Neutral polish. The colored shoe polish isn't necessary, and the neutral gives it a better shine on top of the dye. I wear a Hellweg pistol belt that is going on eight years of service. New, they are like wearing a two-by-four around your waist, but this one is so old it is soft now. I've used the Lexol/dye/neutral treatment on it more or less annually, and it shines like a new dime.
The butter lamp is the KNN mark - out of curiosity, is the bowl blank, marked with a single dot, or with a "/\" mark? My Malla is also a KNN, and it would be hard to imagine a better blade.
Don't quite get your "back seam" reference - Not the laced seam on the front? From the texture of the leather in the frogs, and the manner in which they are laced, it is my edumacted guess that these are finishead off the sheath, put on while wet, and allowed to shrink in place. Mine are all tight on the sheath, will only slip about 1" up or down, and the finish underneath appears to bear this out. If the laced seam gaps a bit, I wouldn't sweat it. That puppy is there to stay
[This message has been edited by Walosi (edited 06-13-2001).]