In this time of conflict, members of both genders take up sword and axe and shield and march to the frontlines. However, due to a long tradition, more men than women become soldiers. As conflicts continue, men become noticeably scarcer in Stormwind, Ironforge, and other Alliance cities. More and more, women perform the tasks traditionally reserved for men, such as working at the forge. The sisters of steel are just such a group of female blacksmiths.
Long experience at the forge toughens the sisters' skin and strengthens their muscles to the point where they can plunge their hands into fire without wincing, and blades rebound from their flesh. Some whisper that these abilities are due to more than just a mundane connection to the forge — that strange and ancient magic is at work. Some sisters claim that they benefit from the blessings of Khaz'goroth, the titan shaper and forger of the world. When the need arises, the sisters of steel lift the weapons they forged and move out to combat their enemies.
The first sisters of steel were Ironforge dwarves, and most members are dwarves. Their allies are glad for their aid, though a bit bemused at their powers. The fact that a few human and gnome women belong to their ranks proves false the idea that their abilities stem from dwarf-only phenomenon. Whatever the case, the sisters' allies are glad to stand by their sides. Their enemies view them with a healthy mixture of respect and fear.
In these troubled days, many sisters routinely leave their forges to patrol areas around Ironforge, crushing troggs and other enemies of their people. Some travel farther afield, supporting the Alliance on distant battlefronts. Others, knowing their strength in combat and seeking to enhance their smithing skills, travel the world in search of rare materials.
Sisters of steel excel at soaking up damage and dishing it out. They wade into melee combat, smashing their enemies with maces and axes as bullets and blades glance off their stonelike skin. The sisters of steel are staunch members of the Alliance, but the rare defector is possible.
The sister of steel has "Skin of Steel". Her skin looks to be made of steel or rock, and indeed at least part of her body is a form of rocky and/or metallic flesh. The sister of steel's weight doubles. As she trains, the time spent training and at forges adds muscle mass, and she becomes stronger. Soon, the sister of steel's impressive skin causes blows to glance away, reducing the damage or negating it entirely. As the sister of steel continues her transformation into stone, she has an increased chance of blocking critical strikes against her, and soon arrows simply rebound off her skin. Note that as this is a supernatural ability, it is negated in an "anti-magic field" or similar effect. If the sister of steel loses her skin of steel ability (temporarily or permanently, for whatever reason), she also loses much of the protection she had gained through transformation reverting back to original self.
In time a sister of steel surpasses her mortality through "Steelflesh Ascendance" and becomes a being of living stone and metal. Her type changes from humanoid to elemental. She gains immunity to poison, sleep effects, paralysis and stunning. She is not subject to critical hits at all. She no longer needs to eat, sleep, or breathe. Her weight doubles (in total, she weighs eight times her original weight). Unlike most other living creatures, the sister of steel no longer has dual nature — her soul and body form one unit. If she is slain, no soul is set loose. Spells that restore souls to their bodies such as raise dead, reincarnate, and resurrection, don't work on her. It takes a different magical effect, such as limited wishes, wishes, miracles, or true resurrection to restore her to life.
- The Sisters of Steel hinted two years before the actual release of Wrath of the Lich King that humans, dwarves and gnomes shared a common "metallic" ancestry.