Mah'alleinir is the war hammer of Perrin Aybara. It is a Power-wrought weapon and its name means "He who soars" in the Old Tongue. It is named after Hopper who died the final death in Tel'aran'rhiod shortly before its creation.
It measures about four feet long, has a large brick shaped head, a long metal handle, and the imprint of a leaping wolf on the side of its head. It is described as resembling an outsized blacksmith's hammer more than it does a "traditional" warhammer, with a wedge-shaped back in place of the typical armor-piercing spike common on typical warhammer designs.
It is the first Power-wrought weapon to be made since the Trolloc Wars, and was made with the help of both saidin (from Asha'man Fager Neald) and saidar (a circle of Wise Ones). When used by Perrin, it feels warm to the touch, but it seems to burn both Shadowspawn and anyone on the receiving end of its blows. It has also proven capable of permanently killing Darkhounds.
"Mah'alleinir" bears a striking similarity in name and description to Mjölnir (pronounced Myol-neer), the hammer used by Norse Mythology's Thor, god of thunder. In the vein of the story, it could be interpreted that the effects of time can cause the name Mah'alleinir to become Mjölnir over the course of several thousand years. This line of thought leads to the possibility that hammer described in the myths about Thor could be the very same that Perrin Aybara forged so long ago, in an Age yet to come, in an Age long past.