Hermod

The son of Odin and Frigg and the messenger of the gods. After the death of Balder, Frigg sought for one brave enough to face Hel, the ruler of the underworld and plead for his Balder's return. The great hero Hermod the Nimble volunteered to make this dangerous journey. He mounted Odin's steed Sleipnir and traveled to the underworld.

When Hermod came upon the gates of Hell, he jumped right over them and entered the great hall of the dead. There he saw Balder and he begged Hel to release him because Balder was loved by all so no-one could miss him. Hel was skeptical and agreed to release Balder on the condition that everything, dead or alive, should weep for Balder.
If only one thing should not cry, then she would keep Balder in the realm of the dead.
Hermod returned to the land of the living and told the gods what Hel's terms were.
But not everyone wept and therefore Balder had to remain in the underworld until the end of the world.

Hermod carries a magical staff called Gambantein.

Read more: http://www.pantheon.org/articles/h/hermod.html