This thread is hella old, and I was a bit of an idiot when making it. But no, leather and studded leather should not be considered as an effective form of protection at all, unless the leather is boiled or it's used as backing for actual armour. There were some other examples but I'm doubtful as to their usefulness, especially considering just how bloody rare they are. Cuir bouilli is an example of a boiled leather coat, and it seemed relatively effective in the English Civil War and later. I believe mostly to protect against sword cuts, where I can see a thick leather doing okay.
Furthermore studded leather exists only in Dungeons and Dragons, and is probably caused by confusion as to the design of a coat of plates or a brigandine. The material is on the outside and is riveted to meta plates on the inside, which gives it a 'studded' appearance.
This is a replica of one of the Wisby coats of plates. I should add here, that they were very rarely made out of leather. Modern reproductions often use leather for some bizarre reason, but in reality they were usually a material, like wool, linen, or silk, or a mixture of the lot. I have a few ideas about why using leather for this is stupid: first, leather is very difficult to repair. Unlike materials that you can just sew together, leather has to have holes punched in order to actually sew. Furthermore leather is an extremely expensive material in this period, especially in such a large sheet, and if you're willing to shell out this much money on leather why not just put silk over wool or have the material decorated? That's actually the third point: leather isn't easy to decorate. You can't weave in heraldry or intricate decorations, and in late 13th and early 14th centuries when coats of plates were used that's important. Brigandines are generally considered to be later coats of plates that are given more shape, akin to one-piece cuirasses.
Butted mail should not be an option either. Ever since its invention in Europe mail was riveted. Butted mail is an artefact of the orient. I believe some Ottoman armours may have been butted, but in general everything was riveted, welded or stamped in Europe. Back then mostly riveted and welded, and riveted would make the bulk of the links. As to the specifics it changed between time periods, giving historians a nice time frame for most mail armour. That doesn't mean to say that, as incorrectly has been said in that doc, butted mail was bad. It was far worse than riveted, but it'll protect you in a pinch. You'll probably still be safe from a cut, though a thrust might bend the links if thin enough.
I generally take issue with trying to quantify resistance of armour, mostly because tests on this subject have often been very biased in one way or another. This thread could probably do with reworking too, but I can't really be bothered.
