Help me! Knowledge (?) is certain for you.
'Here I carve for you (runes of) help, Bofi. Runologists Mindy MacLeod and Bernard Mees translate the amulet as follows: Likely worn around the neck, the Kvinneby amulet is a small copper amulet found in Öland, Sweden that dates from the 11th century and features an Old Norse Younger futhark inscription that invokes Thor and his hammer. Finally, another proposal connects Old Norse Mjǫllnir to Old Norse mala meaning 'to grind' and Gothic malwjan 'to grind', yielding Mjǫllnir as meaning ' the grinder'. Another proposal connects Mjǫllnir to Old Norse mjǫll meaning 'new snow' and modern Icelandic mjalli meaning 'the color white', rendering Mjǫllnir as 'shining lightning weapon'. Old Norse Mjǫllnir developed from Proto-Norse * melluniaR and one proposed derivation connects this form to Old Church Slavonic mlunuji and Russian molnija meaning 'lightning' (either borrowed from a Slavic source or both stemming from a common source) and subsequently yielding the meaning 'lightning-maker'. The etymology of the hammer's name, Mjǫllnir, is disputed among historical linguists. 4.4 Relationship to the swastika and Icelandic folk belief.4.3 Nordic Bronze Age and potential Proto-Indo-European origins.4.2 Temple instruments and ceremonial significance.4.1 Latin sources: Adam of Bremen and Saxo Grammaticus.4 Scholarly reception and interpretation.3.1 Hammer pendants, rings, coins, typology, taxonomy, and Eitri database.In the anime, the Mjölnir never controls any thunder or lightning, aside from releasing lighting when sealing Loki.In the anime, Issei never faces any difficulties in using the Mjölnir.Mjölnir's name is derived from a Proto-Germanic form *meldunjaz, from the Germanic root of *malanan "to grind" ( *melwan, Old Icelandic meldr, mjǫll, mjǫl "meal, flour"), yielding an interpretation of "the grinder crusher".Though the original hasn't shown to be able to shrink, in the anime, Mjölnir, after Issei transferred the boosted power from Boosted Gear increased in size after being used to attack Loki, as well as displaying being able to seal the evil god after being struck. The Mjölnir replica was also able to increase and decrease in size after the wielder's aura is imbued into it as shown when Issei channeled his demonic power in it, while it is unknown if the original can do the same, it can be assumed. The replica of Mjölnir, which was lent to Issei has displayed the same lightning-based abilities as the original, as well as having power close to the original. Mjölnir is one of the weapons that can only be wielded by gods, which is capable of generating and controlling thunder and lightning capable of defeating other gods. Mjolnir after being charged up with the Boosted Gear Like in the novels, the Mjölnir is handed to Issei who transfers the Boosted Gear's power into the hammer, striking Loki with the hammer and defeating him. The real Mjölnir is summoned by Odin to the battlefield where the young Devils, Irina and Rossweisse are battling Loki and his monsters. In Volume 13, it was explained by Surtr Second that Mjölnir was forged by the Dwarves from the Ívaldi Tribe for Thor. The hammer itself is light as a feather and bears no weight, except for those who have any evil feelings, as the hammer can only be wielded by those with a strong and pure heart. However, this was overcome when Issei used Pailingual on Akeno to find out about her past and contacted the Chichigami by accident, who later granted him a blessing that allowed him to use the Mjölnir replica and defeat Loki, after striking him with the lightning produced by the replica boosted by the Boosted Gear. Despite this aid, Issei (even in Scale Mail armor) faced difficulties in using the Mjölnir replica due to its sheer weight. Despite being a replica, it retains the same abilities as the original, however, as it is still classified as a divine weapon it couldn't be used by Issei without the initial assistance of Baraqiel and other people.
The original Mjölnir doesn't appear in the Light Novels, instead, a replica was handed over to Issei to assist him in combating Loki and Fenrir. In the anime, when having its power boosted by Issei's Boosted Gear, the Mjölnir gains a glowing design expanding throughout the hammer. There is a Norse symbol on its middle piece. Mjölnir is a giant hammer that has a black outer frame with a blue structure throughout its entire design from the head to the handle.