Mjölnir

Mjǫllnir — “the grinder” or “lightning”

The short-hafted hammer forged by the dwarves Sindri and Brokkr — the single most commonly worn amulet of the Viking Age.

The dwarf Brokkr's bellows were bitten by Loki as a fly — hence the short handle.
Mjölnir always returns to the hand that throws it.
Hammer amulets multiplied in direct response to the Christian cross.

Origins & Attestation

Over a thousand Mjölnir amulets have been excavated across Scandinavia, England, Russia and Iceland, in silver, bronze, amber and iron. Their numbers surge sharply in the 10th century — exactly as Christian missionaries pressed north and the cross became a common pendant. The hammer became a statement of allegiance as much as a charm.

What it means

Mjölnir is the boundary weapon: it stands between the ordered world of gods and men and the giants of chaos beyond the fence. But it is not only destructive. Thor's hammer hallows — it blesses marriages, sanctifies boundaries, consecrates the newborn and the dead. In Þrymskviða the hammer is laid in the bride's lap to sanctify the wedding, and that is the moment Thor seizes it back.

How it was used

Worn at the throat on a cord or chain, raised over the marriage bed, over the pyre, and over land claimed as one's own. Iron rings hung with tiny hammers were kept at temple doors as oath-rings.

The sign today

The primary identifying symbol of contemporary Norse heathenry, recognised as a religious symbol by several national militaries and by the U.S. Department of Veterans Affairs for use on headstones.

“Bring the hammer to hallow the bride, lay Mjölnir on the maiden's knee.”
Þrymskviða, st. 30