- "Engrace a collision of elements upon the enemy's soul."
Nibelung Valesti is an ability exclusive to Aeth in Final Fantasy: Legend of Balance. It is a Truth ability and is learned at level 58. Aeth performs five hits on enemy, each with different elemental affinity: fire, ice, wind, lightning, and non-elemental respectively.
Nibelung Valesti is possibly named after Purify Weird Soul and Soul Crush attack from Valkyrie Profile series. This reference is further implied as the message which appears when performing the ability, "Aeth: This shall be engraved upon your soul.", are the same words used in the ability's incantation by Lenneth in the first Lenneth.
Nibelung is probably a reference to Der Ring des Nibelungen, which tells the story of Brynhild and Sigurd, on which Lenneth's and Lucian's story is loosely based. In and of itself, it does not mean anything, probably being used for the reference it evokes. Valesti could be derived from the Latin verb valere, which means "to be strong". The combination is therefore both a reference to Norse mythology and to the strength of the attack. (Source: Nibelung Valesti at Valkyrie Profile Wiki.)