There were issues at small sizes that might help with darts and which have definitely been handled for bolts. Contact area always influenced the chance of penetration, but there was a division at one point that made small contact areas round up, so any small numbers were just getting washed out. I'd still need to test darts. Elastic clothing still has some too-magical properties that I might even deal with before this release if they keep coming up.
Yeah, I considered adding additional structural material information systematically, but too late. By the time I had finished the initial mat/tissue rewrites and thought about doing it, it was already too far in the cycle to go back and add it without blasting myself out by an unknown time yet again. Now it might be worth it to get it in in pieces, so it can query the item (or ground or tissue or whatever) for the unified information, and failing that, fall back on the specific tags. Anything that doesn't involve a long delay would be good, and it's definitely called for. At the same time, we could consider some of the ideas that have been floating around about material quality and so on, so that you could have more minute changes occur to smelting/forging/whatever processes that give the material rather than the item some quality. It should be possible to do it without jumping off another cliff.