Hrothmund's Blessing is an Alteration and Illusion spell in The Elder Scrolls III: Bloodmoon that surrounds the Nerevarine with a shield of elemental frost, providing resistance to Frost Damage, and damaging nearby adversaries for 10% of the effect's magnitude. It also increases the Nerevarine's chance of evading physical attacks. This includes hand-to-hand combat and melee or ranged weapons, but has no affect on magic.
This spell may be granted by the spirit of Hrothmund the Red, the first chieftain of Thirsk, when attempting to pick up his axe. This may be performed at the request of Svenja Snow-Song during the quest called The Mead Hall Massacre.
Also this spell can be acquired on the PC by using the console command:
Player -> AddSpell "hrothmund blessing"
The axe is found inside Hrothmund's Barrow, which is sealed and requires the Nerevarine to utter the name of the Fell Wolf that killed Hrothmund, Ondjage, to gain entry. This can be learned from Louis Beauchamp during the quest called The Patchwork Airship.