Two distinct classes of knives were in use by Vikings. The more common one was a rather plain, single edge knife of normal construction, called a knifr. These are found in most graves, being the only weapon allowed for all, even slaves. Smaller versions served as the everyday utility tool, while longer versions were likely meant for hunting or combat or both. Weapon knives sometimes had ornamental inlays on the blade. The construction was similar to traditional Scandinavian knives. The tang ran through a more or less cylindrical handle, the blade was straight with the edge sweeping upward at the tip to meet the back of the blade in a point. The knife apparently played an important role for all Scandinavians. This is evidenced by the large number of knives found in burial sites of not just the men, but the women and children too.
The other type was the seax. The type associated with Vikings is the so-called broken-back style seax. It was usually a bit heavier than the regular knife and would serve as a machete- or falchion-like arm. A wealthier man might own a larger seax, some being effectively swords. With the single edge and heavy blade, this somewhat crude weapon would be relatively simple to use and produce, compared to the regular sword. A rather long tang is fitted to many examples, indicating they may have had a longer handle for two-handed use. The smaller knife-like seaxes were likely within the fabrication ability of a common blacksmith.
The Seax was in widespread use among the Migration period Germanic tribes, and is even eponymous of the Saxons. It appears in Scandinavia from the 4th century, and shows a pattern of distribution from the lower Elbe (the Irminones) to Anglo-Saxon England. While its popularity on the continent declines with the end of the Migration period, it remained in the British Isles where it was taken up by the Vikings. The large, sword-like seaxes are primarily found in connection with Viking settlements in England and Ireland, but do not appear very commonly in Scandinavia.