What does the saying “Nibelung Valesti” translate into?

I don’t know about the entire phrase, but Nibelung is used in German to refer to the East Germanic tribe known as the Burgundians (or Burgundes) that settled Worms, Germany. On the other hand, in Richard Wagner’s opera cycle “Der Ring des Nibelungen,” (also German) Nibelung is used to mean “dwarf”. I hope that helps.

P.S. Several reliable sources tell me that Valesti translates to “You were worth,” but that’s in Italian.

Something in a Video game.

But the original Nibelung are any of a race of subterranean dwarfs whose hoard of riches and magic ring were taken from them by Siegfried.

I think it might be a made up term – all that I can see is what you probably know already – the name of a spell or an attack variation in a video game called Valkryie.