Thor's hammer "Mjölnir" is certainly one of the most important Viking symbols. If not the most important. According to Norse mythology, Mjölnir is the most powerful and intimidating weapons in existence.
Although this was used as a weapon by the Thunder God, this symbol was also used in ceremonies to bless marriages, births and funerals.
Despite the chaos that Mjölnir was capable of, this symbol represents blessing, dedication and protection.