E-mail address on my profile.
RonLosey@hotmail.com. Send the files there.
I know I have read that obsidian cuts steel. It's like a diamond cutting glass. Nothing short of heavy plate will stop it, and then it is more because the attacker is not strong enough to drive the obsidian through the metal - not because it would not work given sufficient force. It will cut chain armors and most scale/lamellar constructions to shreds - they're just not heavy enough to stop it.
And by the way, a steel axe will cut a tremendous amount of metal. I have done the test cuts on that, and so have others. A four-pound axe will go through European chain armors like paper, and up to 1/16 inch hardened steel plate (a good deal heavier than most armors) will either cut/shatter or crease to the point of penetrating the target. Granted, it takes a really solid hit to do that ... but still, it makes quite a mess. From what I read, obsidian blades have many of the same properties. I unfortunately can't give you the sources on those at the moment, because it's just been too many years since I saw that material. I'll try to find them again.
Obsidian itself is sharp and relatively light, but a string of stones on the side of a wooden club is both heavy and not too sharp. The ragged edge produced by various oddly-shaped stones has nowhere near the slicing properties of a smooth razor edge. The stones themselves tend to drive in and hang in meat (and armor), creating excess resistance. The same problem appears with modern serrated edges - they're fine for slicing bread, but not worth a dime on a fighting knife. They leave an ugly wound, but nowhere near the killing power of what a heavy sword with a smooth razor edge will do. (You're from Mexico - I thought all Mexicans knew how to fight with a knife.

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Obsidian weapons are also heavy, because while a steel blade is maybe a quarter inch thick and two inches wide, the Aztec clubs were a heavy board an inch and a half thick and four inches wide, lined with stones an inch thick. For similar length, the total volume of the weapon is about 20 times greater - so mass per unit volume tells you nothing.
I'll start by modeling the arrows using either obsidian or heat-treated flint. I think the current mod only uses the "barbed arrow" model. We can add the others for variety later. Although Spain had a strong archer tradition in the Roman period, I doubt they did much with longbows in the Americas - so Spanish steel-tipped arrows were likely quite rare. (Unless, of course, someone got hold of their crossbow bolts and reused the tips in longer arrows, or traded for such supplies.)
And as for this rescale, I don't think you have any idea how much I intend to change. I'm talking about a rebalance around European long swords doing cut damage between 50 and 65 points. Plus or minus 2 or 3 points is going to be nothing. I'm not tweaking things - I'm rebalancing the whole game... hopefully to a point where unarmored humans don't take 10 arrows and keep fighting.
(For preview, Onin-no-Ran should be releasing this combat model soon.)
Standing by for the files.