WEAPON ENHANCEMENTS
+1 Quality, +2 Quality, +3 Quality, +4 Quality
Ok, sure, though I might be inclined to do something more like +1/+0, +1/+1, +2/+1, +3/+1 (+hit/+damage) to represent 4 levels of quality.
Kris Blade, Serrated Blade...
Neither of these are really enhancements. They are more like drawbacks. What you call a 'Kris Blade' is more generically called Flamberge. Mostly it's decorative. They were believed to have a variety of combat advantages, but mostly they looked cool. In theory they produced a very slightly wider cut on a thrust, but they do so at the cost of increased weight (and hence, lower velocity, and consequently usually lower penetrative capacity since velocity overwhelms mass at some point in the kinetic energy equation) and increased cross sectional area (again, lower penetration). They are however slightly lighter that blades of equivalent width, but mostly the purpose of width in a sword is to provide improved strength and slashing capability - not piercing blows. In theory they disconcerted opponents when they were used to parry, but that was mostly lack of familiarity and probably overstated anyway. In any event, the fad died out fairly quickly. It's expensive to produce weapons of this sort, and they give minor or no advantage.
It's worth noting that during the period that the Kris was an actual battlefield weapon of importance, it was straight bladed. The wavy bladed form only became dominate after people stopped using the Kris for anything other than ceremony and personal defense - precisely the times when being showy and intimidating is more important than being effective. And despite claims that the wound is more effective, actual executioner's Kris remained straight sided.
Mostly the effects of flamberge on combat ability are too fine of resolution to matter in D&D's abstract combat system. If I was going to have them be meaningful in my own system it would be something like, "Get a worse sword for a circumstance bonus on intimidate and perform checks in combat."
The serrated blade is even worse. You aren't going to find many examples of this in real world weapons at all, because serrations are mostly used in sawing. In general, you aren't going to have a lot of opportunities to use a sawing motion on a target in combat. What they in general do is weaken the blade and make it 'bind' to the target when you hit. So what that means is that you stick the weapon in something and then can't pull it out again, which leaves you helpless as your now enraged victim's friend tries to lop your head off. The only exception I can think of is in purpose built 'sword-breakers' where the goal was off-hand defensive parrying and binding of the opposing weapon - in general actually breaking a sword with a sword breaker is possible only if the sword is made of poor quality steel. Otherwise, the force placed on your hand/wrist is generally large enough to break your wrist or wrest the weapon from your grasp before it actually breaks the sword. Again, this is a level of detail usually well below that of D&D's granularity. Unless you track individual maneuvers at the level of parry/riposte/bind/high/low/advance/retreat/etc. all serrations really do is make your weapon worse, and even then any advantage only occurs in certain situations and your weapon is generally less effect outside those sitautions. I'd let serrations assist in off hand parry and weapon/shield binding maneuvers, but otherwise they increase weight, reduce damage, and cause problems on critical hits/lethal blows with getting your weapon back.
Tempered Steel...Folded Steel...Razor Edge
Doesn't this overlap with 'quality'? I mean what does high quality mean if the steel is of less quality? Isn't at least some of the advantaged of tempered steel or folded steel that it holds a better edge and punches more easily through armor?
Studded Bludgen, Spiked Bludgeon
In D&D and in 1e particularly these differences are often generally the difference between weapons. See for example: club, mace, morning star.
The bayonet on a rifle was at the end of a long metal rod allowing it to be used like an awkward spear. It generally interfered with the accuracy of the weapon and was only mounted when necessary. Historically, based on an analysis of injuries, it was almost never actually used. The bayonet accounted for no more than about 1% of battlefield injuries. It's use seems to be mostly psychological.
On a crossbow, how you cock this thing now that you've got a knife sticking out where the foot stirrup usually is? Assuming you dismount it, how effective is it going to be? I can find no evidence anyone ever made one of these things, which makes me think it probably wasn't that effective. I suspect people just carried a short sword or hand axe. Still I guess you could make one, though in actual combat I'd expect that the first time you entered melee with it, you'd end up with a splintered bow.
