The Sagas, Religion, and what we beleive caused the Viking age to be.
What we as historians know about the Vikings we have learned through Archaeology, reading the various Sagas, the Saxon Chronicles, the memoirs of Ibn Fadlan, and others who had direct contact with the Vikings. I urge you to read passages from all of the works that I have just mentioned because the truth most likely lies somewhere in the middle. The sad reality is that what we know about Viking combat is very little. Most of the fighting styles out there that are called “Viking” are educated guesses at best. What we do know is that the Vikings were strong, intelligent, ambitious and proficient with weapons of many types. Keeping that in mind we can use common sense and learn how they may have fought through experience and many hours of practice.
Much of what we read in the Sagas tells us little about the exact details of what happened between "They met, they insulted eachother for a few minutes, they fought, and one or more of them died."
Here is an excerpt from The Laxdale Saga Chapter 19 - Hrut Comes to Iceland:
The men of Salmon-River-Dale now jumped off their horses, and got ready to fight. Hrut bade his men not trouble themselves about the odds, and goes for them at a rush. Hrut had a helmet on his head, a drawn sword in one hand and a shield in the other. He was of all men the most skilled at arms. Hrut was then so wild that few could keep up with him. Both sides fought briskly for a while; but the men of Salmon-river-Dale very soon found that in Hrut they had to deal with one for whom they were no match, for now he slew two men at every onslaught. After that the men of Salmon-river-Dale begged for peace. Hrut replied that they should surely have peace. All the house-carles of Hoskuld who were yet alive were wounded, and four were killed. Hrut then went home, being somewhat wounded himself; but his followers only slightly or not at all, for he had been the foremost in the fight. The place has since been called Fight-Dale where they fought.
Here is another from the Saga Chapter 49 - The Death of Kjartan
Bolli stood aloof with Footbiter. Kjartan smote hard, but his sword was of little avail (and bent so), he often had to straighten it under his foot. In this attack both the sons of Osvif and An were wounded, but Kjartan had no wound as yet. Kjartan fought so swiftly and dauntlessly that Osvif's sons recoiled and turned to where An was. At that moment An fell, having fought for some time, with his innards coming out. In this attack Kjartan cut off one leg of Gudlaug above the knee, and that hurt was enough to cause death. Then the four sons of Osvif made an onset on Kjartan, but he warded himself so bravely that in no way did he give them the chance of any advantage.
Here is another from Chapter 2 of Grettir's Saga
Now Onund laid his ship alongside one board of the ship of Thorir Longchin, about the midst of the fleet, but King Harald laid his on the other board, because Thorir was the greatest bearserk, and the stoutest of men; so the fight was of the fiercest on either side. Then the king cried on his bearserks for an onslaught, and they were called the Wolf-coats, for on them would no steel bite, and when they set on nought might withstand them. Thorir defended him very stoutly, and fell in all hardihood on board his ship; then was it cleared from stem to stern, and cut from the grapplings, and let drift astern betwixt the other ships. Thereafter the king's men laid their ship alongside Onund's, and he was in the forepart thereof and fought manly; then the king's folk said, "Lo, a forward man in the forecastle there, let him have somewhat to mind him how that he was in this battle." Now Onund put one foot out over the bulwark and dealt a blow at a man, and even therewith a spear was aimed at him, and as he put the blow from him he bent backward withal, and one of the king's forecastle men smote at him, and the stroke took his leg below the knee and sheared it off, and forthwith made him unmeet for fight. Then fell the more part of the folk on board his ship; but Onund was brought to the ship of him who is called Thrand; he was the son of Biorn, and brother of Eyvind the Eastman; he was in the fight against King Harald and lay on the other board of Onund's ship.
There are many other stories that include battles and combat within the sagas but again, there is not much in there regarding specific fighting styles or moves. It is up to historians, archaeologists, and (Living History combatants for lack of a better term) to try and unlock the secrets that quite possibly in the end may prove to be lost to the ravages of time.
The Religion of the Vikings:
We can’t really discuss the Vikings without mentioning the religion that governed them and so deeply influenced the direction of their lives. It also had much to do with their ambition, spirit, and search for glory through combat, and conquest.
I firmly believe that the Viking age was a direct result of the expansion of Christianity northwards. The crusades that went south to the "Holy Lands" could be compared to the crusades north into what would later become France, and Germany and the Pagan territories of Scandinavia where just as much death and destruction of the culture of the indigenous peoples occurred. The attack on Lindesfarne occurred in the year 793. Charlemagne’s reign of terror which culminated in the murder of 4,500 Pagan Saxons who had been taken as captives. The Massacre of Verden, Bloodbath of Verden, or Bloody Verdict of Verden (German Blutgericht von Verden) was a massacre of 4,500 captive rebel Saxons in 782 just 11 years earlier. I believe that the rule of physics can be applied to history as well "for each and every action there is an equal and opposite reaction." I believe that massacres such as the one that occurred in Verden and the continuous encroachment into pagan territories finally made the Scandinavians realize that they needed to act. Their actions were swift, bloody and merciless but no more merciless than those of the ambitious and cruel Charlemagne.