Penitent, the Blade of Courage, is the legendary blade of Trinimac used in ancient times. Statues depicting Trinimac often show him holding his sword, and worshipers of the god swear by it for aid. The Vosh Rakh, an Orcish extremist faction, named themselves after the blade's Orcish name as they considered themselves a manifestation of it.
The Poetic Edda is an ancient collection of poems, stories, and legends that depict the extensive history of Skyrim, which is why it earned the moniker, "the living history of Skyrim." For an untold amount of time, bards and skalds have contributed to the Poetic Edda, which is often kept by the Bards College of Solitude.
The Prismatic Core was a powerful crystal that powered the Prismatic Weapon, created by the willing sacrifices of many priestesses of Meridia. It was given to the forces of the Ayleid city-state of Delodiil during the early First Era, so that they could defeat their Molag Bal-worshiping enemy of Abagarlas and destroy the Mortuum Vivicus. The destruction of Abagarlas was successful, but the weapon was ruined in the attempt. The crystal powering it was salvaged, although drained of its power, and five Ayleid heroes set out to the Dwemer ruin of Mzeneldt to hide the crystal so that the forces of Bal could not find it. The priestess Valasha sacrificed herself to re-power the crystal, with the rest of the heroes giving their lives to safeguard. It was later recovered by the Fighters Guild in 2E 582 and re-forged into the Prismatic Weapon. The Prismatic Weapon was used by the guild's champions to destroy the Mortuum Vivicus once and for all.