Bowie Knives?

[Delcan]

Why the emphasis on masterwork? A masterwork weapon, per RAW, is "a finely crafted version of a normal weapon". The Bowie knife was a large utility knife made to be a tool useful for all occasions, including a fight if it came right down to it. A whole lot of them were produced - they weren't created one at a time for unique buyers. Some were, mind you - but those were the masterworks. Everything else was a normal weapon.

Now, that having been said, there is the old story about how James Black (the guy that made Bowie's Bowie) might have tripped over the recipe for Damascus steel somewhere along the line, and you could incorporate something similar into your D&D game. The original-made Bowies might be masterwork, because of some long-lost crafting technique.

Also note that there is nothing inherently special or unique about the Bowie knife's clip point. Per the same wiki article you reference, clip points are common on many knives. (I've got a clip point on a cheapo pocketknife in the kitchen drawer somewhere.) You want to talk about superior stabbing power and depth, pull out one of these.

Balance-wise, a crit range of 18-20/x3 is absurd. There's a reason that all the weapons with a crit range of anything more than 20 are only x2 damage. You can have an improved crit range on a weapon, or you can have improved crit multiplier on a weapon, but you can't have both without magic or feats. If you want something akin to a Bowie knife, I would reflavor a dagger - the Bowie is a slashing/stabbing weapon, smaller than a short sword, and fairly throwable, all of which is covered by "dagger" without having to add anything.

I would go on, but this is really just a repeat post anyway.