The Heimdall gear style is one of the four Epic level weapon gear sets for the Raider class (along with the Tengaar set) for the Viking faction in For Honor, added in Season 2.
The weapon shares its name with the god Heimdall, whose duty it was to guard the Bifrost, and to keep an eye out for signs of the Ragnarok. If Ragnarok were to happen, then Heimdall was to sound his horn to begin the war.