Weapon Composition

[seasong]

Update: The current final rules are in post #56.

Spoiler:  

The armor divisor for stone, wood, horn, and tooth cut/imp weapons means that a sharp stone axe is worse at penetrating armor than a blunt stone axe. Which sort of makes no sense to me. Below is an attempt at a new set of rules for armor penetration and damage.

Armor attempts to convert all kinetic damage (cr, cut, imp, pi) into crushing damage. The larger the surface area the attack is spread over, the easier this is. A slashing weapon (sharp claws, whips, and similar) has a conversion value equal to DR×3; a long chopping weapon (most swords) of DR×2; a short wedge chopping weapon (most axes) of DR×1.5; and an impaling or piercing point of DR×1.

If the damage is equal to or less than the conversion value, the damage is treated as crushing in all ways. Eliminate any bonuses to damage for a fine or very fine edge, and then increase final damage by +1 (it is effectively a flanged crushing weapon), and use the crushing damage rules for all purposes. If the damage exceeds the conversion value, treat the damage normally.

Tough Skin does not affect these conversion rates (but you still suffer from effects which require a 0-damage scratch, skin contact, and so on).

Any weapon composition which creates an (0.5) armor divisor, instead doubles the conversion value. So a stone-tipped arrow would have a conversion value of DR×2 instead of DR×1, and a stone-edged sword would have a conversion value of DR×4... but would still function as a bludgeon of similar weight (as opposed to being less effective than said bludgeon).

Human skin is considered to have DR 0.25 for this purpose (round 0.5 or higher up).

Does this seem reasonable?

[Dunadin777]

Originally Posted by seasong

The armor divisor for stone, wood, horn, and tooth cut/imp weapons means that a sharp stone axe is worse at penetrating armor than a blunt stone axe. Which sort of makes no sense to me.

It makes perfect sense. It's a mechanical representation of cleavage (geological cleavage, not the awesome kind), which is the tendency of a mineral to split under pressure. In the case of what GURPS would call stone, once its shaped into an axe head it is much more vulnerable to shattering and breaking or at least chipping, which reduces the impact of the weapon. The more blunt it is, the less shear the edge, the more likely it is to retain its shape and impart its full impact to the target.

Having a sharp edge only helps if you actually can keep said edge. Otherwise it's a waste of impact. Literally.

[Trachmyr]

I have been using an expansion on the Edge Protection rule from Low-Tech for some time now, to good effect.

Generally a cutting weapon has to do more than 2xDR to get cutting modifiers (I've modified this to 1.5xDR for swung/Unbalanced attacks), Impaling/Piercing has to do only more than 1x... if stone, add +100% DR to the threshold, so cutiing needs to do more than 3xDR (2.5x if unbalanced), and impaling at 2xDR.

Any Armor with "Tough Skin" is ignored in this calculations.

This is quite similar to what you've done.

I like the idea of slashing vs. cutting damage, I might play with that a bit.
I think stone should add +1xDR not double current values, otherwise it becomes too ineffective for cut/slash.

You start by saying tough skin doesn't matter, then give humans .25 DR... I say pick one or the other.

Overall, I agree... and I might update my version a bit with some of these ideas.

[Turhan's Bey Company]

Originally Posted by Dunadin777

It makes perfect sense. It's a mechanical representation of cleavage (geological cleavage, not the awesome kind), which is the tendency of a mineral to split under pressure.

This is technically a bit off. The armor divisor is a consequence of the cryptocrystaline nature of the materials used to produce the sharpest stone blades, which is almost the opposite of having cleavage planes.

Still, the essential point is correct: GURPS Low Tech doesn't distinguish between sharp and not-so-sharp stone tools as such. It distinguishes between flaked stone tools (which historically have sharpness as just one of their properties) and ground stone tools. The materials used to make flaked stone tools can provide exceptionally sharp edges, but they're also exceptionally fragile. They cut soft materials easily, but wear down quickly even with light use and will chip and even shatter if used on harder materials, losing that sharp edge instantly instead of cutting.

[Dunadin777]

Originally Posted by Turhan's Bey Company

This is technically a bit off. The armor divisor is a consequence of the cryptocrystaline nature of the materials used to produce the sharpest stone blades, which is almost the opposite of having cleavage planes.

Heh, if you say so. I bow to your assertion due to not bothering with geology for about a decade, except when my geologist friend lets something tedious slip in conversation. :)

Still, RAW seems to be a perfectly accurate way of illustrating reality. And if a proposed house-rule to change it is considerably more complex than the RAW which is at least 'close enough', I know I would stick with RAW.

[seasong]

Originally Posted by Dunadin777

In the case of what GURPS would call stone, once its shaped into an axe head it is much more vulnerable to shattering and breaking or at least chipping, which reduces the impact of the weapon.

It is hard to believe that a flint axe head can ablate that much damage without completely shattering... much less suffering no ill effects at all. Nor is it easy to believe that the flint axe head is chipping upon impact with soft human flesh.

I understand that ablation occurs. But given that a soft object can - at best - halve damage in a collision, it is difficult to believe that an axe head could reduce damage by more than -1 due to its ablation.

Originally Posted by Trachmyr

You start by saying tough skin doesn't matter, then give humans .25 DR... I say pick one or the other.

Actually, I said Tough Skin does not affect the conversion rate. That does sound similar to "Tough Skin does not convert damage," but is in practice quite different.

DR ×+1 seems like a better idea than doubling, although it requires a bit more math.

[Ulzgoroth]

Originally Posted by Dunadin777

Still, RAW seems to be a perfectly accurate way of illustrating reality. And if a proposed house-rule to change it is considerably more complex than the RAW which is at least 'close enough', I know I would stick with RAW.

RAW would have stone-age hunters preferring bludgeons to spears, because stone-tipped spears are no good at penetrating large game.

[seasong]

For what it's worth, I am not concerned with more complicated rules for this purpose, and the rule above is based on the similarly complex edge protection rules in GURPS Low-Tech.

[Dunadin777]

Originally Posted by Ulzgoroth

RAW would have stone-age hunters preferring bludgeons to spears, because stone-tipped spears are no good at penetrating large game.

No, because stone-age hunters wouldn't take spears for the damage--you take it for the advantages inherent to spears, namely reach and defensive mobility. Even if it does less outright damage, it'd still be preferable to use a weapon that can drive prey and can cause bleeding. Most primitive hunting of large game was more a matter of endurance and tailing wounded game as it bled to death anyways.

Your typical dragon fight is not a good litmus for the usefulness of a stone spear.

[Dunadin777]

Originally Posted by seasong

For what it's worth, I am not concerned with more complicated rules for this purpose, and the rule above is based on the similarly complex edge protection rules in GURPS Low-Tech.

And I don't mind complicated rules. But, if they are complicated they should really add something to the play experience. I just don't see that here. I see a minor speed bump in fringe cases to enforce a falsely linear appreciation of combat weapons. An edge isn't always the best option to kill someone outright, especially when non-metal weapons are concerned.