Aegislash is the evolved form of Doublade and the final form of Honedge. It can be evolved from Doublade by using a Dusk Stone.
Aegislash's name is most likely derived from the words "aegis" which means shield and "slash".
Generation of kings were attended by these Pokemon, which used their spectral power to manipulate and control people and Pokemon
Apparently, it can detect the innate qualities of leadership. According to legend, whoever it recognizes is destined to become king.
Aegislash along with its prevolutions is the only Pokémon with steel/ghost unique matchup.
Aegislash and Tyrantrum are both Pokemon designed by Hitoshi Ariga. While the two Pokemon are entirely different, they share a shiny color-scheme that references the Mega Man Series. Shiny Aegislash shares the same colors as Rogue, while Shiny Tyrantrum shares the same colors as Mega Man. Both from the Star Force series. This could potentially be a referene to the fact that Rogue has a posessed sword.