I know the fact that Kirito's Dual Wield in SAO and Skill Connect in ALo was an award or 'was' awarded by the system for being the top player with the fastest reaction Time.

And that Yuuki can pass down her insane sword combo (Mother's Rosario) to other players like Asuna. But

how did Sonno Yuuki Created this Skill or is it just a skill which came from her converted account because she was in other VRMMO?

Is there a chapter in the light Novel / Manga where this is discussed?