Freyja's Falcon Cloak:

Freya, the Germano-Norse goddess of fertility, was said to possess a magical falcon cloak. Wearers of the cloak were transformed into a falcon.

The poem Þrymskviða features Loki borrowing Freyja's cloak of feathers and Thor dressing up as Freyja to fool the lusty jötunn Þrymr. In the poem, Thor wakes up to find that his powerful hammer, Mjöllnir, is missing. Thor tells Loki of his missing hammer, and the two go to the beautiful court of Freyja. Thor asks Freyja if she will lend him her cloak of feathers, so that he may try to find his hammer. Freyja agrees:

"That I would give thee, although of gold it were,and trust it to thee, though it were silver."

Loki flies away in the whirring feather cloak, arriving in the land of Jötunheimr. He spies Þrymr sitting on top of a mound. Þrymr reveals that he has hidden Thor's hammer deep within the earth and that no one will ever know where the hammer is unless Freyja is brought to him as his wife. Loki flies back, the cloak whistling, and returns to the courts of the gods. Loki tells Thor of Þrymr's conditions.