This is one of my favorites...
It's a hand-forged Damascus blade made by a blacksmith friend of mine in a coal-fired, hand-pumped forge, and hammered and folded on an anvil.  These blades can run up to $100 per inch...  He made the blade, and another friend hafted it and made the sheath.
I'm not overly fond of the sheath, but haven't gotten around to making a replacement yet.
I won this knife in a shooting match with my flintlock rifle several years ago.  I had a choice of either the knife or a rifle.  10" blade, razor sharp, and nice and light.

I've really weeded most of my weapons down to where all of the ones I have are pretty prized.  Rattlesnake-backed bows, flintlock rifles, muskets, and pistols, old shotguns, etc...  This would be the toughest to replace though.