Thor's hammer has a short handle because the dwarf working the bellows was interrupted in his task by Loki, disguised as a fly!
Thor, the Norse god of thunder, was supposed to have a very impressive hammer with a long handle that was intended to be wielded with both hands – a weapon worthy of a god.
The making of Thor’s hammer started with a bet.
Loki bet his head that the dwarf Sindri and his brother Brokkr would never be able to make items as beautiful as those made by the Sons of Ivaldi, who made Odin’s spear.
They accept the bet and get to work.
Sindri put some iron in the forge and told his brother to never, under any circumstances, stop pumping the bellows until he returned to remove the iron from the forge.
Bokkr faithfully pumped the bellows as instructed.
Loki, with his head on the line, disguised himself as a fly and as soon as Sindri was out of sight, he bit Bokkr on the eyelid.
The bite was so hard that it caused Bokkr’s eyelid to bleed!
The blood ran into his eye. He stopped pumping the bellows just long enough to wipe the blood away, but when Sindri returned and removed the iron meant to be Thor’s hammer, the disruption caused the handle to be much shorter than intended.
Despite the flaw, the hammer was so beautiful that Bokkr and Sindri won the bet. They did not take Loki’s head, but sewed his mouth shut instead.