Warning: contains spoilers for Wonder Woman #773
Wonder Woman has gained a new weapon, the legendary Asgardian sword Gram, a gift from the Norse hero Siegfried. Diana may traditionally be associated with Greek legends and mythology, but in the comics, she's been exploring another divine realm - Asgard. DC's version of the Realm Eternal is more heavily influenced by the Norse legends than rival publisher Marvel Comics', with DC's version of Mjolnir even cursed rather than blessed.
Initially amnesiac, Wonder Woman found herself struggling to fit into life in Asgard, and swiftly discovered the Cycle of Ragnarok had been disrupted. During her adventures, she found herself falling in love with the Norse hero Siegfried (or Sigurd), and when her adventure was over in Wonder Woman #773 he suggested he should return to Earth with her. Diana knew Siegfried's place was on Asgard, though, because the Ragnarok Cycle - now restored once again - was still too fragile. But she took a gift from Siegfried with her, the legendary sword Gram.
It may not be as famous as Thor's weapon Mjolnir, but Gram is nonetheless crucial in Norse mythology. Described as being "all decked with gold and gleaming bright," it was given to Sigurd by Odin the All-Father himself in a tale remarkably similar to the British legend of King Arthur and Camelot; Odin thrust it into the Barnstokkr tree's trunk, enchanting it so only one person could draw it out, "and he will find out for himself that he never bore in hand a better sword than this." Gram caused great problems for Sigurd because it was coveted by kings and warriors alike, but it was also used in some of his most memorable adventures - notably to slay the dragon Fafnir.
Siegfried's gift is a precious one, marking his love and respect for Diana as a warrior. Gram will serve as a reminder of his feelings for her, as well as the good Diana did in restoring the Ragnarok Cycle; Siegfried's spirit was briefly left incorporeal, unable to be restored because the Valkyries were wearying of their duty, and if not for Diana he would have been trapped as a ghost for all time. There is, of course, an additional irony to Siegfried's giving Diana Gram; in the original Norse legends, this sword gradually became a symbol of chastity, and Siegfried's desire for Diana is palpable.
It remains to be seen what powers DC's version of Gram will possess, but certainly, it will be powerful - and likely sharp as well. In the legends, the blade was so sharp and durable it cut an anvil in two while being forged. No doubt Wonder Woman will find such a weapon useful.