Several weapons and armor in Diablo II have actual historical counterparts. While it is a fantasy setting and especially the elite tier items are mostly fanciful names with impressive numbers, the developers did borrow a number of names of arms and armor that did exist in ancient and medieval times. While these aren’t seen to be fit as part of the trivia section, I think it is interesting to look at what place these things had in history, and I plan to try to detail most of these in a multi-part blog post. Most of these have articles in wikipedia, and while I'd be loathe to recommend these articles in and of themselves, many of them do provide concise information for history buffs.
While considered the lowest form of protection 6-10 layers of linen or other fabric is not only good at absorbing blunt trauma, it is also quite resistant to slashing trauma. In fact, it is often better protection than leather of similar thickness. While popular during the Middle Ages and the Renaissance, tabletop gaming like Dungeons and Dragons had decided that leather armor was superior. This could be the subject of a lot of speculation, so I’ll leave it at this.
As mentioned above, while regarded as superior protection, the cured leather coat pictured in the icon would have been suitable as a backing for scale mail or under a coat of chainmail, but in and of itself was inferior protection to quilted armor. Typically, layers of cloth provide better cutting resistance and absorbs impact better than a similar thickness of leather. Still, any warrior who has stared in the face of death during battle knows that even a piece of leather can mean the difference between life and death.
Hard Leather Armor
Leather gained a chitin-like hardness when boiled in water or oil. For a centuries in ancient times, and armor could be fashioned out of this which gave leather additional resistance to slashing trauma. However, it should be noted that while it is documented as a battlefield armor, it seemed to fall out of use when metal armors became more common. Possibly due to iron and steel providing better capabilities to penetrate armors such as these.
Ironically, it is doubted that studded leather had ever existed, but was confused by Hollywood costume designers with another armor called brigandine where metal plates are riveted to the inside of a leather backing, only the rivets being visible. The studs in and of themselves would not be functional as protection. The icon for the armor, however, suggests hardened leather lamellar with the rivets piercing the top and the bottom of each plaque.
While this didn’t exist in Medieval Europe, a number of Asian cultures had sewn metal rings to a cloth or leather backing to improve resistance to slashing trauma. It was not, however, any more effective than its backing against blunt or piercing-type damage.
This wasn’t an enormously popular armor, but it did see use in ancient times especialy amongst Roman Legionnares as well as amongst other cultures. It is constructed by having small hardened leather or metal plates sewn to the outside of a cloth or leather backing. Because the scales also tended to be riveted in the center not to mention significantly overlapped, it would be stiff and heavy.
While the breastplate was seldom worn alone until after the Renaissance, it would certainly provide great protection to the torso, and lighter than a properly constructed shirt made of chain links.
This was one of the most popular types of armor during Medieval Europe until plate armor came into common use. It provided a very tough yet flexible barrier to slashing trauma. If worn over a suit of quilted armor, it would also have good resistance to bludgeoning damage. While its weakness is against narrow piercing objects, a properly constructed suit with riveted rings would be at least resistant to this form of trauma as well.
Often associated with samurai, it is armor constructed with strips overlapping of metal fastened to each other and then riveted to a backing. The armor in the icon is not actually a “splint mail” armor, but a form of laminar armor, more specifically modelled after a samurai's breastplate .
While I'm no expert I believe that light plate, like the breast plate, would provide great protection for the torso, but metal plates alone would provide a lot of vulnerabilities for attackers. It was typical to wear chainmail to cover the parts that would be vulnerable, but an adventurer certainly would benefit from a suit such as this.
While this armor did exist, it was rarely referred to as such. Although the term originates from tabletop RPGs it is meant to represent a suit of full plate armor that is custom made to provide excellent protection while not sacrificing mobility. Articulated sections like knees and elbows have chain mail sections to help protect the body when the joint was open and vulnerable to attack. Also, the plates pictured for hip protection, called tassets, also helped permit a good range of leg movement without sacrificing protection.
This is a broad term to describe any instance which uses metal plates against their body to protect someone from being harmed by weapon attacks. So even scale mail can be regarded as a form of plate armor. As a matter of convenience, however, scale mail is differentiated by the size of the plates used in its construction. Ironically, the armor’s icon is a form of laminar, laced together on more than one end to make it less vulnerable than scale armor.
As plate sections became more popular and evolved into plate armor, ridges and flutes became more and more prominent to help deflect blows. At one point, it became so elaborate and heavy that it was suitable for parades and little else, but for an adventurer with gold to spend, would be hard pressed to find better protection.
Again, a tabletop RPG term used to describe parade or jousting armor. This kind of armor was so heavy that it was only worn for tournaments and parades. It also impeded movement as it was only intended for holding a lance on horseback or walking. The icon, however, looks like the field plate model with some added leg protection.
I'll add this one for completist reasons. I'm sure that the devs felt that they needed one more category for armor, and its design, not to mention the elaborate embossing, looks much like parade armor to be worn by someone with a high status and a lot of gold. In fact, later gothic plate would look much like this icon.